We have two rabbits that we rescued about 6 weeks ago. Since they are rescues we don’t know their exact age, but our best guess is that they are around 2. They have been together almost all of their lives and came as a pair due to the fact they were already bonded. They were also both spayed before we got them. They have always gotten along great and although they occasionally manage to scare each other, have only ever cuddled and cleaned each other. That all changed tonight when they started humping each other. Both bunnies took turns humping so it doesn’t seem to me to be a dominance thing. One bunny would become submissive and there other would mount. Each time we clapped loudly and yelled no, but they did not respond. (They will usually stop their bad behavior at this command). Since they did not stop at the clap, we physically removed the mounted bunny. The act never seemed overly aggressive and once stopped they did not immediately go back to humping. Also as I said they seemed to take turns humping and the other bunny seemed very submissive. This is the first time we have noticed this behavior, but they are left together in their room during workdays and so we don’t know if they have been doing it behind our backs

The only other thing I will add is that we decided we needed to get them more used to us handling them and tonight they were each handled a few times and might have been stressed out from that. That being said, they were running around the house and doing binkys both before and after the humping. 

Any ideas? Should we be concerned that it will get more aggressive?