i have a '03 TL with 49K miles. it was just in for service and the dealer mentioned that i might want to get the timing belt replaced. he said it goes by mileage OR age, and the car is 8 years old. so, which is it....miles or age???

 

The answer is: Yes. Both matter. The belt will deteriorate from both wear (miles) and age. Having said that, average miles/year would put you at about 8 to 10 years for the recommeded service interval on the timing belt/tensioner/idler pully.
Find a friend who has done this on any honda vehicle and DIY. The cost difference and education are huge benefits. The single biggest challenge is the crank pulley nut. The rest is just hard to reach stuff resulting in sore hands.

 

Like said above its Age or Miles which ever come first. Age is harder on rubber than miles so at your age i would highly recommend having it done sooner than later. If it breaks odds are you will need a new motor as these are interference motors.