I think that extremely loud gurgling along with discomfort in the bunny is what’s a problem. Their tummies make a lot of noise during digestion, normally. Also, no sound at all (if you put your ear to their abdomen) is a bad thing.
A few mornings ago, I gave Java his salad like always, and when I was trying to fall back to sleep (he has me whipped to feed him much earlier than I would normally wake up), I heard these LOUD tummy sounds. The apartment was dead silent, and he was laying on his tummy against the hard plastic flooring, so it magnified the sound by a lot, but it was very loud. His house isn’t far from our bed (we’re in a studio), but still, it’s pretty loud if I can’t sleep through it. When he would stand up, it wasn’t nearly as loud (because the plastic was enhancing it), but it was still extremely loud.
But Java’s tummy is almost always REALLY loud after eating. The fact that he’s totally normal, no pain or discomfort, and it happens after nearly every meal, keeps me from being worried.
If you’re seeing changes in behavior, or obvious signs of discomfort (hunched over during the tummy gurgles, etc), then definitely go to the vet asap.