Master cylinder leaking

[enigma]

I just put a new master cylinder on my 93 civic, and there is a screw with a rubber grommet on the side of the MC that is leaking.
Does anybody know what the purpose of this thing is, other than to frustrate me?
I did tighten it, i'll have to wait till tomorrow to see if it is still leaking.

[Epic Tuning]

Sounds like the bleeder. They come loose some times in the box. It should be fine now you tightened it. Good luck.

[enigma]

There was a dopey o-ring around the head of the bleeder, that would have never worked, i replaced it with a crush washer, and all is fine now.