overheating, ? Options

[jayi12-15psi]

Lately my engine has been running warm, it's not getting too hot, just almost to the top of the little temp. emblem(as opposed to being on the little wavy line). I replaced the radiator in august, and it started doing this a few months later, so I took it to a mechanic. The mechanic found a small leak when he pressure tested the system(it was a hose he tightened it, and filled the radiator back up with coolent). Then about a weak later it started doing it again. I seem to be losing a small amount of coolent, is it possible for coolent to somehow disapeer in a pressure tight system? Because I can't seem to find a leak.

Thanks for listening.

[CheesyLobster]

bring it back to the mec. its probably either the thermostat or there is an air bubble in your coolant. try running the car with the radiator cap off and rev the engine a little and squeeze the top hose. be careful because it may geyser a little but thats kind of what you want for getting out a bubble if there is one.