I went to check my Hydro reservoir and noticed that there was a significant amount of oil residue all around where the cap is. I checked the tightness of the cap and it was very snug. This condition has happened before but i wiped the top of the reservoir clean and the problem didn't occur until now.(approx 50 hrs. later) The filter was changed recently and the correct amount of oil was added to the reservoir.Is this a case of the oil getting too hot and boiling over or is the seal bad on the cap??