Bullying is normal, I have 2 boys who have been together for a year and they still rumble and pester each other every day. If they are not biting and fighting and drawing blood they are fine. It's normal behavior for boys I think. Mine "seem" like they can't stand each other, but when we hold one they will "call" each other across the living room. When one had surgery and had to be kept fairly inactive the other had to be hand fed too because he missed his buddy and won't eat enough.
I find mine get more edgy if they don't get enough floor time, so keep up floor time and like I said, unless they are rolling around fighting they are fine. Make sure their cage is big enough and you have 2 of everything.