If the priest who baptized you was in some way unfaithfull (examples abound today)... I can at least see why human logic would cause someone to question the validity of the sacrament. This fails to recognize Who it is who takes the oath, but is at least understandable. Neither theology is correct, but one is more interesting than the other. I can see mis-informed cafeteria Catholics having the same problem.
Imagine the odds. :-)