I've had a little bit of yellow leakage from anus. i think this is fecal leakage due to hemorrhoids (because i've had problems with internal hemorrhoids before), but could it be mucus or a sign of an infection? no pain or other symptoms?

Hemorrhoids alone usually do not cause anal discharge. It could be an infection, especially if you are at risk for STDs. Your profile identifies you as male: get seen ASAP if you have had receptive anal sex, or if the discharge continues more than 2-3 days. You also chose "anal swelling" as a topic tag. That also could be a sign of infection, or maybe just your hemorrhoids.