Answer:
Yes, it can and should be corrected. There's no need to issue a revised closing disclosure before closing, but the consumer should receive it at the closing.
However, if that rate lock extension fee was not on a loan estimate issued before the closing disclosure (as might be the case if the rate lock extension was executed just before the closing disclosure was issued), there could be a problem, since the closing disclosure will have been the initial estimate of that fee (in lieu of a revised LE). At closing, it could be argued that the fee when correctly disclosed creates a 0% tolerance error, requiring a lender credit cure.
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