Anyone else's Z do this?

[2013Zsport]

So almost every time my Z gets hot if I'm driving hard or stuck in traffic and it starts getting hot I blip the throttle and the rpms will slowly float up by its self to about 2000 rpms and slowly come back down. Not like when I first take it out, ill blip the throttle and the rpms will go up and come right down quickly. The way any off my other cars do. So I'm wondering if anyone else has this happen to them or if this is a well known problem, or if it's common and is nothing to be worried about? Please help!