The overflow/expansion tank does handle this. But there are minor losses that over a period of year(s) may require the system to be topped off. And it will likely show up in the cold weather. The pressure cap will release air when the system goes from a very cold to very hot state, this is normal. But some liquid will be carried over in that burp. After a year or 2, you might have to add a cup or so of coolant. If your adding quarts/gallons or more than once a year, yes, you have a problem.
The dealer should be checking this during routine maintanance, but if they are using the cold coolent level point when they are checking it hot, then it's underfilled. My recommendation is to ONLY fill to the minimum (cold) point, no more. I have found that if you fill to anything more then min recommended, it will only burp out anyway.
Last edited by KeithS; 01-01-2013 at 12:00 PM.