What engine size does it have exactly? ie:- 3.0 d4d?
Have you checked the engine bay or timing cover for any stickers or even yellow/white paint with writtten mileage/date changed? as some garages tend to do that rather then use a or the provided sticker with the t-belt kit instead to write down the mileage when done etc?
Ok..if there no signs of anything on the timing cover or engine bay to suggest the timing belt has been done recently..then it would be well worth having it inspected..normally when that timing belt warning comes up its a bit like a service light - its there to tell you the timing belt is due for renewal - and once the belt is changed along with the associated pulleys that belt runs on - then the timing belt light is reset - I do agree it is a bit of strange mileage to pop up so it "may" have done before...as far as i know on the 3.0d4d engine if thats what you have in the vehicle its every 100,000miles or 120months which ever comes first..Like i say have the belt check out and see what its like..if its suspect then certainly have it done. aswell as check the engine bay etc for any signs that a previous garage may have written down the mileage/date when done before etc just incase...I do hope this helps..If you require to ask anything further then please do so before you rate