Yeah, I would seal those holes however small. Great with the temp gun. I would double check that interior tub temp with the temp gun and a accurite therm/ hygrom. It's fine to check your eggs on a weekly basis to check the incubation medium for dryness, the eggs for integrity and any abnormalities but you have to be cognizant of the temperature fluctuation as you do this. Make sure to snap those lids back on too.