Sounds like he has learnt this new skill and is wanting to try it out. When DD had learnt to roll from back to front she would do it in her sleep which would then wake her up which them became playtime...

I found that once she started rolling I made her sleep in a "safe sleeper" - you know the thing you put newborn babies in to keep them in position. Because it has raised sides to keep her in place it made rolling over in her sleep difficult. Also by the sounds of it he might have now grown out of his bassinet and as he is rolling hitting the sides of it would wake him up and this might be a trigger for him to think it is time to wake up for a play.

Hopefully your night sleeping boy will be back very soon.