After coming back from holiday when I cranked my car after it's been sitting still for 4 weeks there were some bad knocks and I could feel the car move and the engine ran very rough for a second. My guess was that all of the oil drained to the sump, now it's back to normal and I didn't have any issues since.
If I was in your sittuation I would do as mickyboy says.
If I was in your sittuation I would do as mickyboy says.