Lenders should now consider themselves on notice that the GSEs have adopted an even more aggressive posture in pressing their representation and warranty rights on mortgage loans they find wanting, analysts say, as evidenced by last week’s announced $330 million repurchase of Freddie Mac mortgages by Bank of America. A Freddie spokesman said that the GSE and BofA “mutually agreed” that the bank would repurchase the 2010 and 2011 loans that were not eligible for sale to Freddie under the terms of the company’s contracts with BofA. Specifically, the loans were underwritten using alternative valuation methods that were prohibited for use in the underwriting of the particular types of mortgages involved.