Somehow today while he was going down to eat his breakfast, Gordon managed to hurt his front leg. I think it might be more up towards his shoulder, as he doesn't seem to have any problems with his actual foot.
He yelped and started awkwardly walking around, and spent the rest of the day with a pretty noticeable limp.
Fortunately, as the day went on he seemed to feel better. I don't know how he actually did it, or what he did, but hopefully he'll be all better in a couple of days.