congrats! And yes, you should consult your Dr.

What can be the cause of spotting/bleeding in pregnancy?

hormone changes, sensitive cervix, miscarriages and so on....The list is endless so you need to consult your Dr. To make sure all is well.

I could be way off here, but i've always heard that pink spotting is ok, but brown not so ok. Definitely talk to your doctor. (shameless plug for midwives: if you went with a midwife, you could just page her up anytime and tell her your concerns!)

yeah your way off because pink means its fresh blood and brown is old blood....Fresh blood is always more serious but in any case during pregnancy any type of bleedin or spotting should be discussed with your Dr.

spotting brown blood" is an indication of old, dry blood that is for some reason in the cervix. The most common reason is if you have sexual intercourse and irritation of the cervix causes a little "tear". Not enough that is comes flowing out, but like when you urinate or you wipe, you might see it on the tissue. Unless you are passing bright red blood and clots, brown spotting is pretty harmless.
Mary 36w6d w#4 boy

Thats put me mind at rest. I went to see the doctor today and he said to keep an eye on it in case it gets heavier. But at the moment its only very slight. Just when I wipe.