I have had that happen with a few of my pregnancies- two of the three that I had it with went on to be healthy little one's arriving, one did end in miscarriage. As your doctor said, it can be normal, but can be a warning sign. I know it is very hard not to worry when you see this, just keep an eye on your body and if you start having cramping or the bleeding gets heavier call your doctor.
Has your doctor ordered any blood work? Also, are you Rh negative? When I went through this, I had blood work done to determine my HCG level, and two days later- it was tested again to see if there was a rise. This helped to reassure me that the pregnancy was going in the right direction when they did go up. I also got a rhoGam shot early on as a prevention measure when I had the spotting (since I was RH negative).
Let us know how you are doing and best wishes for you and baby!
I had this with my first pregnancy. Yes, it's very disconcerting. I actually had spotting all throughout my pregnancy with that baby. He was born 10 days past his due date. :>)) Try not to worry! Unless the pink turns red, begins to increase and you have severe pains, then I'd think it's normal.
Keep us in the know!! Congrats!