It's possible. How heavy is the bleeding? I've had bleeding at 4 weeks with a pregnancie that turned out fine and that miscarried. If it's fairly light and only lasts a few days it's likely OK, but if it begins to get heavy with clots it's likely a miscarriage.
I would go to your ob immediately. I had a miscarriage with my last pregnancy and I found out I was pregnant at 4 weeks I miscarried at 9
Two faint line pregnancy test **