Really? Can you imagine a man assuming a woman 6 years younger wouldn't be interested. I think most people wouldn't be shocked by an age gap up to about 10 years.
To clarify, I don't think there's anything inherently terrible about a bloke going out with a woman six years older than himself (of course I don't!).
Although I can recall a seemingly lovely ex colleague - seriously obese, bald, had a heart condition, looked 20 years older than his chronological age, on NMW - being absolutely outraged when a friend set his 34 year old self up on a date with a very attractive 40 year old. 
The issue in this case is a) we're on a postgrad course where the average age of the female students seems to be around 23. I have the ultimate baby face and I think he's pegged me for late 20s, so is in for something of a shock when he discovers how much older than the other students I am.
b) If it became a relationship and he wanted kids, I'm hovering around the top end of the age range for that.
However, if anything comes of it and I snatch him from the jaws of a nubile 23 year old in my course, I'll march straight back to this thread to let peeps know. 