🤷‍♀️37 weeks4days possible mucus plug?

Ugh I hate that I am even posting this, but interested...

I had sex last night around 8, now it is 3 pm. Any chance this is day old semen or is it the mucus plug? It does have a little bit of brownish blood in it and felt very strange coming out.

I know it doesn’t mean labor is imminent or anything, just curious.