Carbon monoxide detector keeps beeping?

My carbon monoxide detector began beeping very quickly, and then, kept going in one nonstop beep until I took the batteries out. On the label, it says that if there's a carbon monoxide problem, it beeps four times with five second breaks after each four beeps. None of the other detectors are beeping. All my windows are open, and the stove isn't on. I don't have a car. Am I in any danger?