I have a 2006 very clean Polaris Scrambler which I bought new. It was showing a coolant level in reservoir slightly lower than "minimum line". I checked coolant in radiator and it was full. The oil level/color does not show signs of taking in coolant. I added coolant up to the "max line" while cold. I then rode the atv around my neighborhood for a good 20 minutes during a recent snow storm. Coolant expanded and was leaking out of hole in top of reservoir cap. Any ideas?

Thanks for your time!