E.W.
I nursed my son exclusively for the first 6 months and I started getting my period within 5 weeks of having him! It is normal to have some spotting, but if it would make you more comfortable, I suggest calling your doctor. Your doctor should be able to verify that everything is normal. According to my OB-GYN every pregnancy is different so this is probably totally normal! As I said, though, just in case- give your doctor a call. Doctors are completely used to handling phone calls and stuff like this!