There is a slight, but distracting antifreeze smell while driving. The windows do not fog, and vehicle is not overheating. My mechanic looked the SUV over and said there "may be a slight leak" but didn't see anything obvious. Because the vehicle only has 23,000 miles on it he does not believe it is time for a heater core. Basically said not to worry about it. Should I just put up with the smell or get a second opinion?