Do you get this only for this particular user, or for others, too?
Could you run this sql query on the EnterpriseVaultDirectory database and post the results?
SELECT MbxSize, MbxItemCount, MbxWarningLimit, MbxSendLimit, MbxReceiveLimit FROM ExchangeMailboxEntry WHERE LegacyMbxDN LIKE '%TerronF%'
Cheers
Michel