Almost every time my gliders first get into their pouch, I can hear them fighting (rustling in the bag and I hear the "fighting sounds" (not cribbing) I think it's the same as the "in-heat" sounds but they're both neutered males so I don't think they're trying to mate... though I suppose that's possible). They don't fight too often outside the pouch but I swear like 90% of mornings I hear them fighting when they first get in there.

I *think* what's happening is that Ash prefers to sleep alone but Ori wants to sleep with him so Ori goes in there and then Ash attacks because he wants to sleep alone. Evidence for this is I sometimes see Ash come out of the pouch and move into a new pouch, and then a few minutes later Ori follows him into the new pouch, and then more fighting ensues.

I've heard that if their making sounds while fighting then it's not the dangerous kind of fighting, but with how often it is I'm worried it will escalate, and (since it's happening in the pouch) if they stop making noise I might not know it's happening.

Both are ~3 months old and have known each other since birth, I got them about a month ago and if memory serves I don't think they were fighting much at first, it's only become noticeably frequent the past couple weeks.

Should I be concerned? And if so, what should I do??

If you're concerned then maybe find a way to watch what they do in the pouch with that.

My sugar gliders do this too
Mine do it while they try to get snug and they keep trying to steal each others spots lol
Its really just them arguing over them moving around when they try to sleep =3