It's a great price for a well maintained TL, but you'll have to do research with the owner and the records specific to the car to be able to know if that's the case. Speaking generically though, that is a fine price and 75k is good mileage for a car approaching 5 years old (from the time is was manufactured).
They are very reliable, again, if properly maintained. Being a Honda these days doesn't exactly define a reliable car, they've had quite a bit of lack luster longevity out of their cars starting with model year 2000 (especially in the transmission category), but that said, as far as i know, from late 2004 on, most of those transmission problems were rectified and resolved, and on a car as late a model as 2008, i would guess even early generation gremlins in any car would have been worked out, since at 2008, this generation TL is on its 4th production year.
Check the papers, check the history and call the dealer where service was done just to see what they have to say...for $15,000, i would also have a Honda/Acura certified PPI done (pre purchase inspection), would probably cost you $75-$100, but its worth it in the long run.