If you dont think they get your millage every time you go in for a recall or an oil change your delusional.. its standard operating procedure, for every manufacturer.
The state collects the same data if you have to go in for regular inspections..
Your speculation is beyond paranoia, they have always done this and they always will... every single auto shop, regardless if they are a dealer or independent will record your odometer readings for there own records.. I am pretty sure they guys whom tinted my windows took an odometer reading, for what? Standard Automotive Business records...
Are you planing on rolling back your odometer or something? You also gave them your mailing address, omg they could just come and steal your cars now since they already know the key and immo code!!! /sarcasm