It is very important that the timing belt be replaced at or before the interval recommended by Acura. Failure to do so can result in a broken timing belt, which could cause severe damage to the engine.
You can find a copy of your owner's manual here http://owners.acura.com/vehicles/information/2009/TL/manuals
or download a PDF from this link:
Please refer to your vehicle's owner's manual for recommended and required replacement intervals.
Page 544 indicates this is an item that should be replaced every 60,000 miles.
Your vehicle should be equipped with a Maintenance reminder that indicates when it is time to service your vehicle. When a maintenance appointment is due soon, you should receive an appointment reminder message on the information display. If you are unsure when it was done last, you should communicate with your technician.