Because Gmail changes like the weather friend.....doing sweeps shutting down accounts randomly...some accounts asking for reverification.....some accounts requesting captchas....happens all the time...it comes with the territory...Why is is that people can't understand that as an account provider we make accounts....we do not hold all the cards...the email provider does....and if that provider decides to shut down accounts or tighten their spam protection it will effect accounts the only thing one can do is make sure your doing everything you can to reduce the chances of you doing something wrong to get the account flagged....(ie like following the directions I sent you).....
This is the reason I an any other provider can only guarantee an account if its unused for 3 days max....Asking for reverifications are the name of the game and they have little to do with how the account was created....we screen all our accounts and even let them sit typically for a few days to eliminate shut downs that may have been precipitated had we done something wrong....
Shut downs/Reverifications in accounts created is 10% How their made, 50% how their used, and 40% the provider itself outside of our control....
With accounts that we let sit for several days after phone verifying them this eliminates any chances of a problem existing with how we created the account...reverification specifically 80% of the time has to do with the email provider itself and has nothing to do with anything either you nor us did....