I've heard the same as you, could be timing belt to be changed at 100,000 or it has had it chnaged at 100,000..
A car with 100,000ks on it can still be in very good condition, average person may do 20,000k/y, = 5 years of driving, go check out a 5 year old car, there will be lots out there that look immaculate...
Either way don't stress to much, the main thing is the condition of it, not the number that the odo says..