I agree with Dr Alex, people like to ask where you're from in the hope that you are from near them etc...
I've been doing tours of New Hall today and I recognised the accent of one of the prospective students on my tour. I asked him where he hailed from and sure enough he came from a town near me and happened to attend the same sixth form college I went to.
It's nice to find someone else from the North of England here as well. I don't think that person was judging you - they just wanted to know a little bit about you.
Anyhow, if the rest of your Visiting Day went well (How did the reception and tours and talks go?)- then I wouldn't let one wee thing ruin your image of the uni.
As has been said several times before here - there are lovely people and not so lovely people in every town. St Andrews is no different in that respect. But given its small size - it's easier to meet the lovely people.