Oil return line fitting leak

Ok after wiping dry the small bit of oil clinging to the fitting I went flying today and upon return took a look at the fitting. Dry as English humor. So here’s what I think happened, when I changed engine oil, I allowed some oil from the filter to drop onto the coolant radiator which is perched below the oil filter on a Zenith 701.  That oil, which subsequently could not be seen or retrieved, was then deposited on the return line fitting by the swirling air under the cowling- but only in flight. The moral of the story is don’t allow any oil to be deposited anywhere it does not belong.

A wise saying. 😌