Lost mucus plug at 27 weeks?

I found my mucus plug with brown blood in it in the toilet while I was peeing and saw a little red blood on my underwear. It looked just like my mucus plug the last time I went in to labor. I went to L&D right away and my cervix is closed so they sent me home. They checked babies heart rate which is good and strong and put me on the contraction monitor and I had 1 contraction in the like 15-20 minutes they had me on the monitor. I didn’t even see a doctor and they didn’t do any other tests like check my urine/blood or see if I was leaking amniotic fluid or at least keep me on the monitor for a little longer. I’ve been getting Braxton hicks a lot more recently too and hip pain. Should I be worried and advocate to be monitored again or should I not be concerned and just listen to the hospital? Has this happened to anyone where they lost their mucus plug with blood early and not went in to labor? Also what could this be caused by?