Yes,
It happened to me just yesterday. Somehow, and I don't have any clue how, some photos of my buddy's new baby ended up on my touch. I did not have these in my iphoto lib. Anyway, check to see if it is asking you to import the pictures. If so, go ahead and import them into iphoto. Once you have done that it will ask you if you want to delete the originals. Click yes. This should remove them from your touch (at least it did for me).
Good luck. If you have troubles, let me know, I can try to walk you through it more.