I have a 2010 Toyota RAV4. I took it to get looked at by the mechanic because my low tire pressure service indicator light came on after I got my snow tires put on at the dealership. They did a great job (the radiator hose was so rusted it fell off when they were looking at my engine, they only charged me for the replacement part not the labor). The light kept coming on several days after I got this done, and I knew my tires weren’t low on air. Anyway, the mechanic ended up saying my right front passenger tire pressure battery needed replacement, which I’m going to get taken care of as soon as I am able, but he noticed my engine sounded weird, and he pulled out a rusted hammer from the engine! How long do you think it’s been there? I only got the car a year ago!
Did you see it fall off? There is usually a metal clip on the hose that could have rust but nothing that would cause the hose to fall off with no pressure in the system.
Honestly sounds like a way for a shop to earn some easy goodwill with a client who doesn’t know any better. Invent a small problem that can be fixed for little/no cost. To be honest the rusty hammer thing sounds similar. In any case, a hammer left in the engine bay is highly unlikely to do any damage so it’s funny if they found it but not like they saved you from anything.