In your case I'm a little concern, not enough to panic. But it shows a change in your cervix. Probably not a huge change. But you are already in bed rest and was had preterm labor. Imma say inform doctor and stay hydrated

I agree with the comment above mine your mucus plug grows back very quickly when you lose it so it doesn't necessarily mean labor is near but with all the symptoms and problems you've been having I definitely don't see you making it till 37 weeks

Probably not. Your mucous plug regenerates constantly. Maybe put a call in and just say hey this happened but I’m not having contractions and see if they just want to check you at next appointment or whatnot. Now if you’re having contractions that’s a whole other ballgame.