HELP! Lost a big chunk of mucus plug!

I was in the shower just a bit ago and I was washing, down there, and noticed a bit of "slimy goo". I didn't think much of it as I've been having an increase in discharge the past few days, so i washed it away and moved on. I then checked one last time before getting out and I noticed more, but thicker this time. It didn't wash away as quickly and I actually had to pull it out a little (gross, I know! I'm sorry). It ended up being about the size of a half dollar, no blood. 
This is my 3rd pregnancy and I only remember losing the plug about 30 mins or so before labor. I'm only 23 weeks but have been having a really sore lower back and Braxton hicks contractions the past week or so.... Also, baby is really low this time around as I still feel him kicking really low in my pelvis...
ANYWAY, Has anyone experienced this this early on and NOT gone into Preterm labor??