Not to sound crass, but have you had intercourse recently? Sometimes a little of his ejaculate can get 'stuck' especially if you rested right after, and come out a day or two later looking like thick mucus, but it isn't your mucus plug. If it IS tour mucus plug there should be at least a small streak of blood in it. At least that's my experience :)
Ur not going to misscarry this far along it would be called a still birth biut thats not ur case. Ur baby is fine, if u feel fine. The mucas could be the mucas plug that u will discharge around labor. Its a way for ur body to let u know to be ready for this baby to come soon. If u still discharge more or ur still really concerned call ur doc and ask about it
it could be part of your mucus plug. some people lose bits and pieces, others lose it all at once. This can happen weeks before labor. Like horsegirl1204 said though, you can call your doctor for reassurance.
You should be fine i wouldnt worry about it as long as its not alot of blood with cramps. But if your really worried about it i would call your doc and see what he thinks