Oil leaks. My FFR had a 302 and after about 1500 miles developed an
oil leak at the rear main area. This was a new crate motor from Ford. My BDR had a 306 and developed a leak at the rear main area and was custom built starting with a brand new Ford Racing block. Both of these leaks were very minimal and not worth the effort to try and fix. I hate
oil leaks and even I was able to put up with it. I think these small block Fords on occasion just like to leak from the rear seal area. I wouldn't worry too much about it unless you think it's excessive.