What Causes Vaginal Discharge Post Non Penetrative Sex?

hi, me and girlfriend were missing around the other night and we didnt really have sex. i did not go into her at all, and i did have a condom on. she is haveing some discharge about 24 hours after. she is on the pill but she kinda missed it up last month. we r just really worryed that she might be pg. cuz we dont know what the discharge is??