Too early for Back to Belly

Kirsten • Engaged💍 Girl mom🎀

So my daughter will be 4 weeks Monday. Twice now I’ve caught her rolling from her back to her belly. I always thought babies weren’t suppose to roll until around 4 months and it was suppose to be from belly to back before back to belly? She’s already went through so many milestones but it’s hard to keep her on her back and hard to sleep when I worry she will stop breathing or suffocate herself since she can’t flip back over yet. Should I be concerned or excited that she’s doing this so early?