Car misfire on warm startup? Single occurrence

Just as a background, my 2001 ford focus had recently been having some misfire issues with the generic p0303 and p0304 codes. About a week ago I changed the plugs, wires and coil as well as the air and fuel filters and then cleared the codes and this seemed to fix the issue and the codes didn’t come back.

However yesterday after driving for about 30 minutes, I parked my car for 10 minutes, went in a store and came back to start my car and upon starting it while in park, it shook and misfired badly with the rpms going up and down with the car feeling like it was about to stall out. I shut off the car and restarted the engine and the problem was 90% gone but still slightly noticeable. When I started driving, it went away completely and drove fine. Then today, there were no issues upon starting it 2 different times throughout the day.

What would cause a single occurrence of a really bad misfire like the one I described from a warm start that was fixed by just restarting the car? There are no codes at all

I am surprised no one answered??

Just that once?