Does the toilet flange need to be bolted?
The bottom of the flange needs to be sitting flush with (or not more than 1/8" above) the finished floor or else the toilet will rock.  The flange should be fastened to the floor.  Dry fit the toilet to make sure it doesn't rock.  If it does rock, use shims to prevent rocking - just tightening the bolts probably will not stop the rocking but will risk cracking the toilet or breaking the flange.