It's that thing of trusting an object that purports to be 'right'. Luckily I can retune very quickly. And at least I noticed :) We did have the 'are you sure the batteries are ok?' and 'was it cheap - are you sure it works?' conversations first before finding the semitone button. The 440 - 441 - 442 thing I looked for but didn't expect a 'let's make you look stupid' button was a standard 'feature'

There is an interesting James Taylor view on tuning - and lots of responses! - here