I've heard that losing the mucous plug is a more reliable sign of imminent labor in first-time moms than in multi-paras. Even in first-timers, it doesn't mean labor is anywhere near, and is generally interpreted to mean that labor is likely to start within the next three weeks. It can re-grow, and you can lose it more than once. I am not any kind of professional, but if it were me I wouldn't worry about this particular sign unless you have a lot of bloody show or contractions along with it.
My second dd was about 3 weeks early - which is about how far from your due date you appear to be right now - and did fine, so that experience makes your mucous plug sound less alarming to me as well. That said, she did have some pretty bad jaundice and using the bili blanket was an anxiety-inducing PITA, so I'd encourage you to take things as easy as you can for a bit just to make sure you get as close to your due date as possible, if not past it.