Where Did That Phobia Go?

So there I was, mug of coffee in hand, feet up on the coffee table, watching a documentary about life behind the scenes at the zoo. There was stuff about the tiger-keepers and the elephant-keepers and the gorilla-keepers, all very interesting, and then the scene switched to the spider-wrangler. He was trying to persuade two large tarantulas to mate without the female eating the male, always a ticklish situation.
Flanders and Swann, Wikimedia Commons          I watched attentively as he let the spiders walk from one of his hands to the other, as they sized each other up. Then the thought crossed my mind: Aren't I supposed to have a phobia about spiders?
          I always did have, for as far back as I can remember. My mother hated them. My aunt loathed them even more. I have myself shuddered with loathing at the mere sight of them and, previously, had to look away if one came on a screen near me. I made diversions through pet-stores, to avoid the glass tanks of spiders. I quickly turned pages to avoid pictures of them. I dreaded, like Flanders and Swann, meeting one in the bath. (Warning for those following the link: the video with this song has pictures of several big spiders.)
          So it was quite a surprise to find myself watching these big hairy spiders cavorting about while feeling absolutely nothing except mild interest.
          My 'phobia' was pretty mild as phobias go. I've heard of people being trapped in their flat because of a spider on the wall above the door. They dared not pass under the beast and had to phone for help. I've never been that bad. I would not be dictated to by an invertebrate, not even by a spider the size of a dinner plate. I would get mad and have at it with the yard brush.
         Though an acquaintance who lived in Australia for a time once flipped down her sun-visor and deposited a huge spider, which had been hiding behind it, into her lap. She screamed and drove off the road, overturning her car. As she hung upside down in the seat-belts, thankfully unhurt, all she could think was: Where is it? If that happened to me, even now, I think the result would be exactly the same. Looking at an expected spider is one thing. Having a huge one unexpectedly dropped in your lap is quite another.
        Previously, I could have walked under a door with a spider above it, but not without a cold grue. And I had always thought, once you had those feelings about something, you were stuck with them for life unless you took active measures to overcome them. I had done nothing.
         There wasn't even any sense of this loathing for spiders fading away. One day I couldn't look at an image of one without hiding my eyes. The next, it seemed, I was happily watching them disport all their eight legs about the place.
          Perhaps this lessening of fear had something to do with all the little black spiders in my garden.
Spot the sparrowpaI've been doing a lot of gardening work over the past year, and every square inch seems to have its own little black, square spider, which scuttles off for its life when my shadow falls on it. I say 'square' because they are quite compact little things which could easily be drawn inside a square. I've seen so many of them, so often, that I've grown quite fond of them. Perhaps they've been therapeutic.
          But I also find myself leaning close to examine the markings on much bigger, leggier specimens that, not long ago, would have horrified me. I now find their shape quite elegant and beautiful when previously I found it nothing but repulsive.
          I'm not saying that I'm keen to have a tarantula sitting in my hand or crawling up my arm, like the zoo's spider-wrangler, who was just showing off. I think that's taking things a bit far. But still... How or why do life-long feelings of loathing and repulsion simply pack up and leave one day, without their owner even noticing?

          I am curious about other's experience. Has anyone else suddenly found a fear - whether it's of heights, birds, open spaces or vegetables - suddenly almost vanish like this?
          And if so, what do you think lessened it?