I don't know, it seems to me Desmond as well as Daniel forgot about the fact that they met in the past. I mean, they didn't recognize each other? That's how I understood the whole thing. So, if you see it my way, Penny doesn't remember now that Desmond asked her for her number back in the past. I'm not sure, though, time traveling theories are always confusing...

__________________
- Does anyone know how to use a gun?
- I think you just pull the trigger.

- Hey kid, what's eating you?
- Nothing, he's at the top of the food chain!
(The Lion King^^)