This could be completely normal but never having had my own cats until now I wouldnt be sure! Occasionally, when the two are really going for it (e.g. completely winding each other up, hightailing around the house) I have noticed Pan panting for a few seconds. This seemed fine to me, after all.. Who doesnt pant after exercise? Although saying that, Schrodinger doesnt. I've started to notice it far more often and it will last up to a minute at times now and on occasion he does it when he hasnt even been excessively moving. He has access to fresh water and does drink.. So am I flapping unnecessarily?