Oil in breather

HI YALL, I RECENTLY PURCHASED A 1992 JEEP WRANGLER ISLANDER IT HAS A 4.O LITER STRAIGHT 6, IT HAS 90,000 ORIGINAL MILES ON THE ENGINE. WELL GOING TO THE LOCAL STORE YESTERDAY I SMELT OIL FROM SOMEWHERE, WHEN I GOT TO THE STORE I POPPED THE HOOD AND LOOKED.I SAW OIL ON THE DRIVERS SIDE OF THE ENGINE COMPARTMENT, UPON FURTHUR INSPECTION I TOOK THE AIR FILTER BOX ALOOSE AND GOOD GRIEF, OIL WAS EVERYWHERE, MY AIR FILTER WAS SOAKED.I WIPED THE COMPARTMENT DOWN GOOD, AND RAN THE ENGINE REVVED IT A COUPLE TIMES, I DIDNT SEE IT LEAKING THROUGH THE BREATHER ANYWHERE. THE NEXT MORNING I CHECKED MY OIL IT WAS NORMAL, I CRUNK IT UP TO SEE IF IT WAS SMOKING, IT SMOKED WHEN I FIRST STARTED IT, I ASUME BECAUSE IT WAS COLD.I DIDNT SEE ANYMORE OIL LEAKS, AND IT DONT SMOKE UNLESS FIRST CRANK IT IN THE MORNING, MY OIL PRESURE IS JUST ABOVE THE HALFWAY MARK. DO YALL HAVE ANY IDEA WHAT COULD CAUSE THAT TO HAPPEN, THANKS ANDR'E