It was late at night when Rose saw the Tenth Doctor in 2005, and the Doctor was deep in the shadows. Also, as it was New Years, Rose may have been drinking and thus not remember. Though, the most likely situation is that since they met for such a brief, seemingly unimportant time in Rose's timeline, she forgot about him, just as any person would forget about the drunk guy on the side of the road on a random night. And also, she may have recognized him. That could have been why she was so surprised. Or maybe she was very surprised, but not in the version of time that the viewer sees in "The Parting of the Ways". "Time can be rewritten."