Coolant Reservoir Leak?

Ever since I bought my Disco the coolant has been steady at about an inch below the max fill line (where the tank is sealed). Lately I've been topping it off so that it is right at the max line, but it will not stay there. The coolant always ends up at an inch below and stays. The only thing I can think of is when I top it off the coolant will leak though the tank's seal when it expands until it gets low enough to stop and stays steady. I don't see and coolant leaks though, are there any other possibilities?

I read where there was a problem with some coolant reservoir tanks. Is yours black, or completely white (semi-transparent)? The ones that are partially or all black had the problem, IIRC.

It's semi-transparent, yellow really. Maybe it was white at one point, I don't know.

Sounds like a leak in the reservoir, if you are using Dexcool you will want to fix it ASAP.
 

Looks like there is a hose leaking near the throttle body. Not sure how that works because I thought it was all circulated by the pump, but it must stop when the coolant gets low enough.

You need to do a coolant pressure test and verify where the leak is, then fix it. If it is the t/body heater unit get a new replacement gasket kit.

There's no doubt that it's leaking there. It looks like that goofy rubber hose to rubber hose connection is leaking in the return line. How did they expect that not to leak?

Only needs to not leak until the warrenty is up dont ya know.