The crankcase breather hose might have been gushing oil for some reason. I'd be a bit wary and do an oil change with a proper new filter. Inspect the old oil as best you can for gas or metal shavings, and look at the filter as well.
Importantly, make sure the shop sells you the right oil filter, and (I'd imagine the 125 has this as well) use the bleed bolt on the motor once you've changed oil, and be on the lookout for your drain bolt to be stuck, just in case.
Reading up on the site will give you some insight into what to look for with these things, but it sounds like your motor was blowing oil for some reason. Either overfilled or a passage is clogged, which would be kinda bad. Make sure the bike is upright when you put oil in the motor or you'll overfill it waiting for it to show in the sight glass.