I didn't know she was behind me until i fired a shot at one that bounded away in front of me. (northern idaho - i had a tag as well as a bear tag). When I fired, i heard a commotion behind me, and saw another one running off. She must have been 20 yards behind me at the time.
She followed me out of the forest for about a mile.
Pretty cool experience really. She screamed at me every 30 seconds or so on the way out, staying about 100 yards away out of sight in the trees. I had a rifle and wasn't nervous but she didn't want me there.
They can be scary at times but rarely attack. I was surprised when i read that nobody in utah has ever been killed by one.