Did you specifically ask her what her feeling was concerning the first date and whither she was inclined to want to continue to explore a possible relationship with you, on your first contact after the initial date?
If you didn't........then you can't fault just her for not volunteering that information. You have as much responsibility in clarifying the situation as she did. Actually more, if it was your concern. Sounds like when you did inquire, she did not back of, become vague or misleading, but answered you directly.
Communication is the key here. If you wish to know something......ask.........the other person can not read your mind and has no obligation to try to read minds or answer a question that has not been asked.
I think this was the OP's point. If I went out with a man and I was no longer interested after the first date, I would tell him that the next time I spoke to him or within a couple of days after the date. I wouldn't keep exchanging a bunch of emails with him. I wouldn't have waited several days until he asked me to tell him that. I simply think that she didn't have the guts to be upfront right away.
She was honest with you , OP, she didn't play any games. Accept it, get over it, & move on from it.
I think the OP has moved on because 1) this is an old thread and 2) he admitted that it wasn't mind games in a later post. People should read all of the OP posts before they respond. Even if she wasn't sure right away, she probably knew that she wasn't interested in him when she didn't respond to him for about a week. She could have told him that sooner instead of waiting for him to ask if she was still interested. She still could have handled the situation better.