"Hearing" doesn't mean acting. You have a history of bias. That you can't see it may actually make it prejudice.
I know that I'm biased, which is why I like to be told when people feel that I am. That being said, I don't care if my bias causes me to declare a guilty person innocent, only the other way around. You could even say that the previous statement is biased, and you'd be correct, except that it is very intentional.