Two things:
1. We know Dyche really, really doesn't rate Patterson. Currently 4th choice, behind even two players that aren't natural right backs in Young and Godfrey.
2. In some of the player interviews, I've seen quite a few of them say how Patterson is by far the loudest player in the squad behind the scenes.
Can imagine Patterson was being a bit boisterous at dinner and Dyche had given him a playful clip around the ear that connected too hard.
I doubt he'd have done the same to most of the other squad members. Highly unprofessional from the manager, especially if it was in public.