The Office of Federal Housing Enterprise Oversight is taking a close look at whether Fannie Mae and Freddie Mac have been charging lenders increasingly steeper guarantee fees in order to boost their earnings – rather than to guard against potential losses. OFHEO began the probe earlier this month in response to a request by Rep. Richard Baker, R-LA, chairman of the House Financial Services Subcommittee on Capital Markets, Insurance and Government Sponsored Enterprises. The…