Thank you all for your replies.

I'm a worrywart at the best of times so I almost freak myself out when he rolls onto his tummy. When he used to doze off while having tummy time I'd always turn him over or just sit and watch him like a hawk.

missymoo84 - I might try and settle him on his tummy. He doesn't like being on his tummy that much so I don't know how it'll go.

Snacks - We're going to just put his dummy back in his mouth without turning him back over tonight to see how that goes, and let him get used to it.

catherinemoses - I never thought about SIDS not being as bad when he can roll himself over.

AliciaK - That would have been so scary right after your friends baby died of SIDS. I'm so sorry to hear that about your friend too.