Our dog bit the newspaper carrier - what should I do?

Hello,

I have a little Westie mix, 1 1/2 years old, 20 lbs, neutered male.

He is of course territorial. He is up to date on his shots, has a microchip, and we have an underground electric fence around our property. We live in town. He's a good little dog, but barks when anyone comes to the door or near the yard.

He's hadn't bitten anyone until today. He was in our front yard barking this evening and I could tell he was barking at someone or something in particular - usually its just a squirrel in a tree across the street. I went out to the front porch to investigate and a female newspaper carrier was walking on the sidewalk in front of our house. My dog was barking at her.

I called him to come in, he continued to bark furiously at her, and to my astonishment the woman then walked right into our yard, onto my property despite the barking dog and approached me with the newspaper. I walked out to meet her partway, and my dog jumped up behind her and bit her on the butt. I wasn't sure he'd actually bit her, I thought perhaps he'd just lunged, but she said 'well, he got me'. I apologized, put him inside the house and she left. An hour or so later she called to say my dog had actually broken the skin, and she wanted to be sure he was 'up to date' as she put it.

I don't think it's much of a bite, because she referred to it at first as a 'welt' until I asked specifically if it had broken the skin and she said it had. I assured her he was up to date on his shots, I apologized again, but she had worked herself up into a state by this time and apparently didn't feel I was apologetic enough, especially when I expressed my surprise that she had come onto my property when the dog was so obviously barking at her.

No more has been said, but if she does decide to turn this into an issue, will my dog be at risk? Will I be liable for whatever claim she might decide to bring?

Help!

Jean