Window Shadow Hang

I've been having a spider dream for two or three years now. I don't know if it really qualifies as a dream, because I'm not totally asleep when it happens. I'll be almost completely asleep, then I see a spider and I wake up. At first I looked for the spider, but I never found it. Eventually I figured out what was going on, that it wasn't real at all.
At first the spider was just like a shadow, because the light from my window was behind it. It would hang down over my face and was pretty large. The last time, though, it was just a little black spider on my wall. It never touches me, and the size and even the color changes from time to time.
I don't have a problem with spiders when I'm awake. I even touch them sometimes, as long as I know they aren't poisonous. So I can't figure out why I keep having this spider dream!