Why is the mtg lender asking for bank statements/tax returns a second time? I thought all the underwriting...?

Underwriting is not automated. Each lender does use an automated underwriting system to do the initial qualification of the borrower, but each file is actually reviewed by an underwriter. Like the previous poster stated, the request is standard, especially for bank statements and tax returns. They want to see that nothing has changed. They will likely pull a transcript of your tax returns from the IRS as well to compare it to the ones that you provided.