I agree, could be relief....looks as though exhaust comes out of it....unless it has been wiped before the picture. IMHO if your lower lube is not white and pasty, you have no water intrusion. I would leave it alone. If you do have water getting in...ie..white lube. Have a shop psi and vacuum test the lower unit. When they put psi on it...(normally 15psi)...they should submerge it...this is if it fails to hold the 15psi for normally around 30min. While submerged bubbles will come from the leaking seal. Check your lube before you do anything...if it checks out...forget about it. Be sure to replace the oring under the screw after you check it...many orings and washers will "seat" when they are tightened...when they are retightened they will not seat the same and a leak can occur. Many people do not realize this and think they have seals leaking when its just that oring....they take it in to have new seals put in and are out $$$. When it was just a 50cent washer or oring. Always look at the simple and cheap first. If you have a bicycle pump and can rig a gauge inline on it you can check it yourself in a bucket or tub. You'll have to rig up some sort of way to seal it...like the rubber end of a air blower on a compressor. I don't know if "air blower" is right...the thing you use to blow yourself off after working the shop...many of them have rubber on the end. you can push that into the drain hole and hold it...have someone pump the bicycle pump to 15psi. If it holds, and you had water in it..I would be its one of the drain seals. Just some stuff to check before you spend any money. good luck...let us know what you find out.
"But if serving the Lord seems undesirable to you, then choose for yourselves this day whom you will serve, whether the gods your ancestors served beyond the Euphrates, or the gods of the Amorites, in whose land you are living. But as for me and my household, we will serve the Lord.” Joshua 25:15