I find that after I have been FMQ for a while my machine starts getting hot. Is this common or is something wrong?

I'd give my dealer or a sewing repair person a call. I FMQ pretty often and have not had this happen.

What machine (brand, model) are you using?
How long are you sewing when it starts to overheat?

Never have had this problem with my Pfaff. But I am a pretty slow sewer and stop quite a bit. Are you pedal to the metal with long periods of constant sewing. Maybe that could be it? I would sure check with dealer.

I think I have found out what caused the over heating. I had my stitch wide and length set at 0. When I started sewing the next day I didn't set them and everything was fine.