6.5 month old won’t roll stomach to back

Baby is rolling back to stomach at every opportunity, and has been since 5 months. But he’s only rolled stomach to back once or twice.

He hates tummy time and seems like he can’t figure out how to get back to his back when he rolls onto tummy.

He’s hitting all other milestones on time or slightly early. He’s been sitting up unassisted for well over a month too.

Should I be concerned ?