HMRC bank acct verification emails : SCAM or..

client filed vat return online, for a very small refund due

this occurs occasionally [ ie refund ], and funds are remitted direct to the same account for which HMRC draw payment when payments are due

today apparenty have received 2 notifications  from    informationpayment.account@hmrc.gov.uk         

to verify the bank account

Seems rather  bizarre given that HMRC have recently over the past 2 quarters refunded and drawn funds from the account which has long been setup with them

Any thoughts greatly appreciated