I suspect that happens to pretty much everyone that hasn't been on a bike for decades.
When I got back into cycling when I was 59, it took about a month of cycling daily (not long rides) for my butt to stop hurting.
Lot's of factors involved (saddle, bike fit, etc.) but I'll guess that after gradually increasing the amount you're riding, the sore butt symptoms will subside.
I live in a northern climate (Canada) and every spring, the 1st few rides result in some discomfort but it always gets better.
Just keep at it...