I asked a girl out, once, and she said yes, then I never heard from her or saw her again. I can't read people worth a damn, so that basically taught me to stop trying.
This is pretty non-standard. However, if it wasn't a deliberate joke on her part (maybe she wasn't interested in a coffee, but saw this as a chance to do something someone would never forget), her behavior suggests that she may have been more nervous than you. A more painful outcome could be, for example, if she laughed at you and then walked away indignantly.
Well the same thing could happen again. I'm imagining that it wasn't particularly pleasant the first time, and just because it (probably) can't get worse, doesn't mean the same outcome won't hurt less. So it seems that one thing he has to lose is some amount of happiness (at least in the short term).
That being said, go get 'em, it probably won't happen again :)