WASHINGTON (Reuters) – The Treasury Department on Friday acknowledged that the number of homeowners in trouble again despite getting help from the administration's signature mortgage aid program was higher than earlier estimates. Treasury officials blamed the error on mortgage finance giant Fannie Mae, which acts as the program administrator for President Barack Obama's $50 billion Home Affordable Modification Program (HAMP), which helps subsidize new terms for borrowers struggling to keep up with their mortgage payments. Treasury said about 4,764 borrowers, who had obtained a permanent HAMP modification, were behind by at least 90 days, while about 53,041 borrowers were behind...