My experience with my 460 (cobra build not completed) is that after sitting for a few months upon the first start-up after sitting, I have the same symptom maybe 5 or 6 drops seem to leak from the rear main seal, maybe 1-2 drops actually hit the garage floor and then after engine is warmed up and subsequent start-ups, no more leakage. I'm thinking the rear main
oil seal is taking a small set or the lip has a small cut/scratch and after sitting for so long allowing the small drops of
oil to escape. The engine is brand new and the
oil pressure is real strong at all temps. But since is stops leaking with more engine start-up cycles, Im not too concerned. I first noticed it when I primed the (EDIT) engine by spinning the oil pump up to full oil pressure before first start-up 2 years ago.