One clownfish resting on surface water on it's side like it's dead?

So... one of my clownfishes are sleeping on the surface of the water, I was so scared when I first saw it! I thought it was dead but no... it seems to be forcing itself to be on its side and lay on the surface of the water.. I heard other peoples clownfishes have done this too o.O are clownfishes really this weird? lmfao i checked my water parameters and everything is fine! my other fishes in the tank are doing fine also lol Should I not worry? should I just wait and see what happens tomorrow? my clownfishes are always sleeping in different spots of the tank, never really one spot.