hmmm if it's a sealed-cartridge bearing it sure shouldnt do that...did you clean it using water under pressure? loose ball hubs weep excess grease sometimes, but sealed (as all surly's i've seen are) means the seal has come unseated. take it to a shop, and ask.

the only times i've seen sealed bearings weep grease is when you have to heat them up real hot so they expand, then you slip them on a shaft and when they cool down they shrink. but I've never seen a press fit bearing like that on any bike.

ps you can replace the whole bearing, axle and nut assembly for $20 or buy the bearings, phil wood bearings for like $8 a pop, just put a set in a stock pista hub I got fer $10, and now rolls like a phil...

word, you know you can pop that lil cover off the bearing itself, use a std jewelers screwdriver , patience and a steady hand. go at it from under the "inner" edge of the cover. toss the bearings in a small jar with an inch of gasoline in the bottom, shake well, blow grit out with compressed air. be sure to pack it FULL of grease when reassembling.

or perhaps you know all this, maybe it helps someone else