How big are your cows? Last summer one of my 18 month old bulls did his darndest to hunch one of my cows that weighed 2090 (I have since sold her). It was painful to watch.
There are a few bigger cows but nothing huge. He also rocks back and forth when he gets up from laying down.
We have not noticed him laying his head down on the cow while in the process.
If he's healthy and getting his job done I wouldn't worry about it..good Bulls ain't cheap....till you go to sell it.. You'll have to put 5 hundred to a grand extra to replace him..might even have to double your purchace price on what you gave for him...