No worries. I charged mine for a week (or longer) before I realized the plastic was on there, and that was almost 4 months ago. I think the only advantage to removing the plastic is that the magnetic connection between watch and charger will be a little stronger. The heat is normal with or without the plastic. My watch is usually cool when I take it off the charger, but sometimes it is quite warm. When I tried watches on in the store they were all quite warm when they took them off the charger.