That's Verizon for you.

 

there should be an option in the phone to auto install updates.

 

Maybe you accidentally accepted the update? I got a notification and rejected it. Haven't been notified since.

I think there's some confusion on the initial notification screen. If memory serves, there are 3 buttons available- 'Update', 'delay', and 'reject'. The delay option allows you to delay the update for a number of hours. Some folks thought the 'delay' button would just delay the notification until later. The 'delay' button actually schedules the update itself- no further notification will be given (I think).

 

Mine automatically updated. I leave it on all night. I turned on my wife's and it had a count down to automatically update but I don't think I saw a delay or cancel option.