Oo, yan talaga ang mucus plug, mama! Normal lang na may slight brown tint especially pag malapit na ang labor, it means your cervix is starting to change na. A few of us moms experienced the same thing at 39 weeks, some nakita namin siya in one go, some gradually lang over a few days, pero sign na talaga na you're getting close! Since you're already 39 weeks and this is happening, best to message your OB or go in para ma-check lang para sure, especially kung may cramping or bleeding pa, just to be on the safe side. Good luck, mama, you're almost there na!