I also had spotting like this with both of my healthy pregnancies all throughout the first trimester. Both of my boys are healthy and all was fine. I did call my OB when this happened and let her know. As others have said, when it is brown blood and no cramping, they are typically not concerned. I did have red blood with my second pregnancy and they had me come in for an ultrasound. The reason for the bleeding was never detected, but the baby was fine. It is worth the peace of mind to call your OB, but spotting like this is very common, especially early in the first trimester.
Hope you feel better!