Ds has been rolling over since easter. He first learnt to roll from tummy to back and did this for a few weeks before rolling the other way (from back to tummy).

Since learning the other direction, he stopped completely rolling from tummy to back and hasnt done since, I wasnt too worried as he was rolling the other way ALL the time - couldnt put him down without him flipping over

Now, all of a sudden, he wont roll either way. He hasnt done so since wednesday (so 5 days) and is just happy to lay there when put on the floor. Even when i change is nappy he isnt interested in rolling. Is this normal? Do they just master something then decide well tha'ts it, i know i can do it so i wont bother??? Should i be worried at all?