Brown tinted Mucus Plug?

I had my first cervical check Wednesday 37+5 didn’t experience any pain during or after till the next day I had minor cramping and a tiny bit of mucus plug lost and that’s it. Today 38+1 I woke up to more mucus plug with discharge but it was all brown. My question is how long does this last after a cervical check? It’s my 4th pregnancy and I’ve never had this happen after a cervical check or this long after. I’ve only lost a little plug with my 3rd randomly and a tiny bit of spotting without mucus plug after cervical checks the day of or morning after.