Fannie Mae and Freddie Mac could face more criticism on Capitol Hill as the Office of Federal Housing Enterprise Oversight has moved to take a closer look at the fees the GSEs charge lenders for guaranteeing mortgages. According to OFHEO, Fannie and Freddie make a tidy profit on their guarantee fees because of their government ties and the duopoly they enjoy in the secondary market. The GSEs charge lenders when they turn loans into mortgage-backed…