My daughter is 3 months old and has just learned how to roll over a few days ago. 

She's doing it all day long and is now spending a considerable amount of time on her tummy (a dramatic increase in tummy time). We did tummy time with her before and she was holding her head up well (most of the time we used a small tummy time pillow under her chest), but now that she's getting to her tummy on her own without a pillow prop, she's handling it much differently. 

She's not using hands for support as much and keeps bopping/bumping her head on the floor (not super hard, but not light either). My concern is that this is bad for her little head. Dad thinks it's fine and that she needs to learn, but I honestly have no idea. 

I haven't spent much time around babies so this is all new to me. 

Should we allow her to keep bopping her head off the floor while she learns? She's on a baby playmat that is similar to a yoga mat. She got rolling over so quickly, but is not using her hands much. It freaks me out to watch her bump her head. I keep cringing but I don't want to prevent her from learning. 

What's a safe way to help her learn? Maybe I'm overthinking things? Should I just let her do her thing?