Big, snot-like blob of reddish brown discharge day after sex???

Is this normal or should I be concerned? For context- I’m on a birth control pill and I finished my period on Saturday… started a new pill pack on Sunday… when I had sex on Monday there was a little bit of red on the sheets underneath me. I’ve never had discharge like this and it was a pretty big blob! I’m wondering if it’s related to the end of my period/ the sex?? Any input appreciated.