Morning Leak

Okay, I can leave about 150psi in my tank at night, but when I wake up and get on the road(about 7:30a) I have to wait for my tank to build up more preasure. It drops down to like 110 or 100. I don't think I have a leak because I can let it sit at school at around 150psi or more, and when I get out of class(usually around noon) it has the same amount of preasue.

Does the coldness of the morning do something wih your preasure like it does with nitrogen?

Btw, I'm running compressed air.