It's normal as long as it's not period heavy blood then your fine I'm 39 weeks and I had light spotting around 32 weeks I told my doctor but he said it's fine could be that your mucus plug might be coming out soon aka the bloody show lol
I've had that all throughout my pregnancy (20 weeks) it could be from a number of things. I'd still call, just to make sure everything is OK. Better safe than sorry, good luck mama!
Tomorrow I will be 31 weeks