Master cylinder tiny hole
for a couple of weeks now I have been noticing a few drops of brake fluid on my radiator guard, but could find the exact spot it was coming from. I thoroughly cleaned it then took it for a ride this morning. Once I pulled back into the garage I could see that the underside of the front brake master was wet, so I looked at the bottom while i squeezed the level pretty hard. Then I saw it. A small bubble came out of a tiny hole on the bottom of the master right next to the brembo logo. Then when I released the lever it was sucked back in. For giggle a cracked the bleeder and some bubbles came out. After i did this it no longer made bubbles come out the bottom.
Anyone know what this hole is for, and what it indicates if there is fluid coming out in small amounts? is it a bad seal maybe, or could it have been caused by air in my lines? The brakes work great still and always have, no issues with performance, only the slow leak. I can't find crap on google.