i think i shouldmaybe help you out, but you already solved it!

That sounds a ton like one problem I had, where I was making a platform game and suddenly one day there starts to be invisible blocks in every level but the first. So I'm going, "Huh?! Why are there blocks here that I didn't put in?" I try to work around it for a long time, making only one level. Then in the end I open up my block object to change it's sprite and...

...The little box labled "Persistant" is checked. The blocks were being carried over into the next room. <sigh> One would think I'd notice that... At least you had better luck then I.