I've noticed this in a few of my games. So far it's only happened with the pegbox, not the xylophone or other toddler/child toys. I tell my toddler to use the pegbox, and he starts toward it, then complains he can't reach it, even though it's exactly where it was the last time he used it and nothing else in the room has changed, either. When I try moving it to another place, he still can't reach it. The only thing I've found so far that works is replacing it.
Interestingly enough, I find that when I move the bugged pegbox the green lines (what are those called, anyway?) that indicate how much space it needs have gone to a full grid square in width. The pegbox and xylophone usually have narrow green boxes, only as wide as they are.
Anyone else having this problem (or better yet, found a solution)? I tried searching for it, but haven't found anything. Replacing it isn't terribly expensive, but it is annoying.