going back in Time thats a moment she will now have..
When she talks about it with the 'other' doctor he wont know what she is talking about and then realise this was a recent visit..

Except that Rose won't be talking about it with Doctor 10.5... A 60 second conversation on New Year's Eve with a seemingly drunken bloke standing in the shadows is not going to stick in Rose's mind is it??

with hair like that!!!

I suppose that's true. Otherwise he wouldn't have spoken to her. I reckon she might remember his voice. It's quite a conumdrum isn't it. She wouldn't have picked up on it before because RTD hadn't come up with the idea to write it yet. Yet now that the story has been written, it's a moment she had for the whole of that year before she met 9. So for the sake of the show I suspect she was far too smitten with 10 to notice that she'd actually seen him before.