Roll over... for real

He finally did it - he rolled over from his back onto his tummy. And now he is doing it as if he has been doing so since forever. We only saw him roll over this morning, but I assume he has done it before - we just weren't there to witness it.
It does make me proud to see him achieve that and it also gives me a sense of reassurance that all is well with him and he is developing well.
The doctor told us to leave him on his tummy as often as possible, so that he can develop and strengthen is arms (he is apparently somewhat weak in the arms). So I was afraid that he would not learn how to roll over, if he was on his tummy the whole time. All the worry for nothing... Naturestill took its course... and I guess that doctors do know what they are talking about most of the time and have valid reasons for their instructions.