With the issue of minimum servicing fees for agency MBS still simmering, Fannie Mae last month lowered its minimum fee requirement for servicing certain adjustable-rate mortgages – a move that elicited mixed reactions from the mortgage banking industry and Wall Street. Fannie on Dec. 15 lowered the minimum servicing fee for most first-lien conventional ARMs to 25 basis points from 37.5 bps. The change now matches the minimum servicing fee for standard 30-year fixed-rate…