Is it normal to ignore someone at a funeral?

Six years ago, when I was a Freshman in college, I got into an argument with a person's who is older than me. Their mother seemed quite upset about this and has not spoken to me since, though she is friendly to other members of my family.

Even at a recent funeral, she refused to look at my direction. I saw her at a party three months later. She was sitting across of me, looked at my direction and noticed me, and moved to another seat while passing a glare back at me.

I didn't think my offense was that bad, and to some extent, I think she is being irrational.