Audi A4 timing belt replacement - letter from dealer

I have an 02 reg Audi A4 Quattro 1.9 diesel. I recently received a
letter from my dealer stating that Audi are changing the recommended
timing belt replacement from 60,000 miles to 4 years (for diesels) for
new Audis and therefore I should get my timing belt replacement done
now , and basically they won't be responsible for the consequences if I
don't. My car has only done 44,000 so this is obviously an additional
expense I hadn't accounted for. Has anyone else had a similar letter.
Should I replace the belt now, wait till the next service (probably
about 6 months/6000mls) or leave it until 60000 as stated in the
maintenance schedule for my car? It seems a bit harsh to indicate that
a part probably won't last as long as designed and nottake
responsibility for the cost of early replacment. Is this really what
Audi are saying or is my dealer just trying it on?