I was bushhogging for an hour or so without incident. I stopped and left the tractor at idle while I investigated a tree fallen in the woods. I came back and mowed on for about 300 yards. I was loping off some low hanging limbs from the seat when I noticed the oil pressure light and the obstructed air flow light along with the flashing warning light that comes on when either of the two warning lights come on. Their is no oil leak, the air cleaner/filters are unremarkable. Their is oil in the crankcase and hydraulics. What is wrong or what do I check next?