Hoping someone can help me out with this problem.

Feb 2019 - Check engine light started to flash, brought it to dealership. They read error code P0300 misfire on the cylinder #4. The dealship changed the sparkplug/spark plug wire changed.

July 2020 - Same problem but with the service stabilitrak message on the dash. Brought it to the dealership but they by the time it got there the error message had went away and they couldn't find it in the system when they scanned the vehicle. Cost $75 because there was nothing to bill back to warranty.

January 2021 - Same problem but with the service stabilitrak message on the dash. This time they were able to determine that cylinder #4 had misfired 375 times and I had it booked in for service. This is what the service tech said
"Tech Cause: Engine light not on on arrival. Scanned codes. Found P0300 engine misfire detected in history. Misfire history on cylinder #4. Removed spark plug from cylinder #4, and found it to look good. Inserted borescope into combustion chamber to check for oil or fuel contamination. Found no signs. Preformed injector balance test and found all injectors to be well within the 9PSI tolerance calculated. Applied dielectric grease to COP union"
Cost $145.04 becuase there was nothing to bill back to warrant (I argued about this for 20 minutes only to waste 20 minutes.)

Other notes, the vehicle never preformes poorly. In fact, if the warning light didn't come on you would have never known there was something wrong in all three occurances. My warranty is going to expire in 8,000 km so I am nervous that something major will go wrong when the warranty expires.

Any thoughts on what could cause this? It doesn't happen often and I'm not to keen on paying money to the dealership only for them to tell me that there is nothing to bill back to warranty.