Yep it's called dieseiling, or after run. Typically means there is a hot spot in the combustion chamber allowing the fuel mix to be ignited, this can also mean there is extensive carbon build up in the chamber as well. I doubt most of our engines get enough use where it would be a major concern.
2 stroke odyssey engine on dyno. Got so hot that when the plug wire fell off it kept running the engine made no difference in power.