Hi , It may be due to deposition of smegma which normally comes out and get deposited more on the grove proximal (below) to glans. Secretion is pshological and increases after thought of act ( which you had few days back). You just need to maintain hygiene and clean with normal soap and water , drink plenty of fluids n use barrier contraception ( condom ). Chances of STI is less as it is associated with other symptoms so if there are other associated symptom as well or symptom does not goes despite of maintained hygiene then visit skin n veneral disease clinic for further management . Hope this ll help Thanks n regards