Spotting

I'm 13 weeks today with my second baby and I woke up this morning with light brown spotting, especially when I wipe (sorry tmi). I called my ob's nurse and she said that it's normal as long as it's not bright red or super heavy and it  should stop soon. I'm not cramping or anything, either. I never experienced this at all with my first pregnancy, and I'm still worried even though the nurse said I should be fine.