@Caseyj,
Yes it actually happened like that. A group of us were good friends (guys and girls) during college. One night my roommate and some of our other friends couldn't go out -- one felt sick; another was working, etc. so it was just me and this one particular guy. So we went to an on-campus event together. Nothing different other than usually there were other friends there.
On the walk back to the dorms, he told me how he felt about me. It was really sweet and I did care for him, but I told me I was sorry I did not feel the same way.
After graduating and out in the working world, we came across each other again and went out to lunch. He sent me flowers and said he still felt the same, I was honest and let him down -- he did not want to remain friends so we lost touch. I am sad about it, but I understand and personally would not want to hurt him further as I care too much for him.
Ask - it can't hurt - if she is vague at all then don't pursue it. I would be afraid she would lead you on. CJ makes an excellent point -- if she really does have different feelings she knows where to find you.