So my 2 male chins have lived together wonderfully for the past year and a half with no problems. Lately (this week) they seem to not be getting along or fighting more often, but only during playtime. One chin starts chasing another until he goes in his usual corner he likes and stands up and growls at the other. When he leaves his corner he gets chased again. It seems like he wants the one whos growling to play with him. When there is no playtime or after playtime, they may start off by being on opposite ends of the cage but by the end of the night are cuddling in their house again. There's been no attacks yet, only standing up and growling at one another. I have had quite a stressful week and have been working late so thier schedule has been a little off, but this isn't the first time thats happened. I'm really worried that something's wrong with one or both of them. Thanks for any advice!