Noticed this as well. When I went to the pet stable to find my missing pets and equipped one of them, it equipped them fine but instead of putting the pet I was swapping for back into my stables, it sent my pet to my temporary item bag. This could be very dangerous and people could lose their pets to the TIB sell timer. I noticed that this pet that was sent to the TIB is not able to be dragged and dropped into the pet bag in your inventory, even if you have room. So he is stuck in a random bag now.