In my experience, jaw abscesses have ALWAYS caused an issue and they are extremely hard to get rid of. We've had rabbits on antibiotics for years to keep them under control, and one rabbit where it was eating away at the jaw bone and leaking pus in to his mouth when the abscess kept returning. (We did eventually have to have him put to sleep but for a brain tumor). One of our fosters developed one that migrated and wound up pushing behind her eye, and eventually got to the point where we had to have her put to sleep as well.
Our most recent case is our foster who was brought to us with abscesses in the throat area, they were rapidly spreading inside him, in places the vet could not feel on exam but saw when she went in to remove them, and they had attached themselves to the jugular vein so not only would that have cause infection to spread more rapidly through the blood stream but if he had moved or twisted the wrong way, it would have caused internal bleeding and he could have bled out in minutes. Luckily, quite a bit of money later, he is doing a lot better now but is still on penicillin injections to make sure his abscesses do not come back.
Sorry, it wasn't clear, is the rabbit on antibiotics at all right now? I would just be surprised that the vet wasn't pushing for any kind of immediate treatment and saying it wasn't a big deal, if the abscess is recurring then there is a problem with persistent infection and it really should be addressed. The last thing you want is the abscess spreading, which is something they tend to do depending on the cause.
