I was at our almost weekly TDR chapter meet on friday and was talking to one of our members who is on here. His Nephew went to tab his KDP and saw what you saw on the bottom of his timing case with an oil leak and figured it busted already. He went and bought a new case and everything to discover it was a casting mark, and the oil leak was one of the seals. Wouldnt sweat it.
(Names not included to protect the embarassed :-laf )