[Warning: TMI] Was it the mucus plug or not?

keriraine

Ok so this is my 3rd child and with my other 2 children, I do not recall losing the plug.  Today I went to pee and there was a little bit of light brown spotting (almost like the last day of a period) and when I wiped there was more mixed with what looked like a glob of snot. 
I'm 32 weeks so I called my doc, they said it most likely wasn't the plug but to keep an eye out (contractions, bleeding, pain, etc.) but if it wasn't the plug, what the heck else could it be?  I haven't had intercourse lately for it to be from that.