Small factory hole in mercury lower unit? What is it?

[hawg]

Just below the cavitation plate where the lower unit bolts on, just an 1/2 inch or so in front of the bolt, there is a very small factory drilled hole about 1/16 or so in diameter. It started to drip a drop of oil every once in a while. I've never noticed it was even there till today I saw a small oil slick in the water thats never been there. Upon inspecting it I found this hole where it came from. It's not a steady, bad drip but a drip. What the heck is it and whats leaking to make it come out there?

Mercury efi 60hp 4 stroke