Cluster feeding with formula?

My son cluster feeds around 6-8pm before he goes to bed where he eats anywhere from almost double to a little over double his usual feedings. He's done this since he was 6 weeks. Now he takes around 8-12oz in like an hour and a half. My pediatrician said it was fine because he's not waking up to be fed again for anywhere between 3-6 hours. I call it that he's getting ready for hibernation but my pediatrician just laughed. He eats till he gets full, spits out or flings the bottle out of his mouth and won't take it anymore which clues me he's full