had the cooling system flush service done about 4 weeks ago. I noticed a slight smell of coolant vapor a few times since after driving. Checked the coolant level and it's at the "ADD COOLANT" line. Definitely didn't have an issue before the service. I'll have to go back to the shop, but does anyone have any insight as to how I might check for a pressure leak? I don't see any obvious signs of leaking - Probably just a small leak allowing vapor to escape.