They are now aware the property is in a flood zone and they must obtain flood insurance. A Map change is not a tripwire requiring you to review your portfolio for loans secured by property that now may be located in a SFHA, but once you become aware the property is in a SFHA then you must start the procedures to obtain flood insurance. See the tripwire flow chart on page 54 of the Mandatory Purchase of Flood Insurance Guidelines.
And from 339.7:
§ 339.7 Forced placement of flood insurance.
If a bank, or a servicer acting on behalf of the bank, determines, at any time during the term of a designated loan, that the building or mobile home and any personal property securing the designated loan is not covered by flood insurance or is covered by flood insurance in an amount less than the amount required under § 339.3, then the bank or its servicer shall notify the borrower that the borrower should obtain flood insurance, . . . .
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The opinions expressed are mine and they are not to be taken as legal advice.