I wouldn't assume a belt will break within a certain number of k's when going over recommended change interval. that belt looks pretty good to me, not how i would expect one with 150,000 ks on it, but hey, its your risk not mine. Actually i wold put money on the belt not being changed considering they sold it at 113,000.
is that a photo of your car's belt or random off the net? if it is your car rotate engine over to see markings on the belt to see if it is a genuine belt. if it is results unclear, if it isnt then you know it has been changed.
timing light method makes no sense, and cant see how that would be of any use.