I read somewhere your plug can regenerate so like pervious post said it could be some of the plug. As long as it's not bright red and in your underwear you should be ok. I'd say lay down and relax, put your feet up and make sure baby is moving. But call your doctor to at least make note of what's going on so they can make sure to check at next app
I had the same thing happen to me around 32 wks.. I went to l&d and my dr. said it was probably a little piece of the mucus plug, and was probably because I had sex the night before. . Just relax and make sure the baby is moving around good. It should be okay. But if your a worry wart like me, it wouldnt hurt to get in and make sure babys okay.
Call your doctor's office or labor and delivery. If it's just a few drops (just when you wipe, not in your panties) it's probably just spotting from a sensitive cervix. Still, it doesn't hurt to check. I'd definitely call but it's not an emergency.