Agreed with above ^^^ though I don't know if they actually put anyone in danger. Sounds more like the part failed and they fixed it, but came up with a cover story to gloss over it. Parts do fail. I've heard more than a few examples of brake pads coming unbonded from their backing. It's not even an issue of parts getting cheaper and crappier with time; it happened to an old g/f of mine over 20 years ago on her K5 Blazer. It was getting a bunch of front end work done at a trusted local shop. They suggested doing the brakes while it was apart, so we said sure. She picked it up and before she got home it was metal on metal due to one of the pads coming apart.
Back to the main point though, that's super lame of them lying to cover up what happened. Would not be using that shop again.
Richard