Engine/transmission oil question concern

I have a 2007 Rincon. Changed the oil exactly as the owners manual states to do so. I added the new filter, then, the oil up to the upper full mark on the dipstick. Ran it for five minutes then let it set for 5 minutes and re-checked the oil level. Everything was fine, but, you let this thing set for a day and recheck the oil it will be about 3/8 to 1/2 inch above the full mark. It runs great like this but not sure how or why this is happening, or, if it is harmful. Only happens after setting in the garage over 24 hours. Anyone have the same problem?