Periodic fighting

[Alibabble]

Does anyone else have periodic dominance issues? I have to separate Gavin and Sweetheart for a couple of days, every two or three months. I probably could just let them argue, there´s no blood, but if I separate them briefly it seems to resolve the problem. I woke up this morning to loud pig noises, running sounds, and other various indications of a fight.

Actually, this was the first time I´ve ever seen them mount each other. I´m keeping an eye on Gavin, he seemed slightly off which may be the cause of all of this. He wasn´t his usually energetic self, so he may be going to see the vet soon.

Any ideas on what causes these periodic episodes? I know that the one before this was triggered by moving to a new cage, but I have no idea what set this one off.