iTunes wont update iPhone 3GS with 4.2

Apple says iOS 4.2 is out, so i took my mothers iPhone and synced it. Last night I updated to 4.1, and today I saw that 4.2 was out so I tried updating it to 4.2 and it says 4.1 is the current verison.

I have iOS 4.2 GM on my phone, i thought it might not work because i had iTunes beta so i download the final release of iTunes and it still says its Up to Date.