ALL Caliper bolts are one-time use! The same goes for cylinder head and conrod bolts.
These bolts use inherent elasticity to keep from working loose. Once that bolt has been torqued once, it's been stretched beyond the point of regaining this elasticity and if reused, could work it's way loose.
Does it happen all the time? Well it probably does eventually, but many have reused them and not yet discovered a failure. But, that's what these people who've had noisey caliper issues are experiencing, albeit short of a total failure... at least to-date.
The question is: For the simple cost of a couple bolts, do you wanna take that chance on your beloved car? I certainly do not.
