A Florida-based firm is offering borrowers the chance to determine if they paid too much on their adjustable-rate mortgages by putting a new twist on an idea that has been around for a while – loan audits. “Adjustable rate mortgages involve changing index values and computer calculations that invite human and software errors,” cautions Mortgage Audit Services, a division of consulting firm Golden & Associates headquartered in Winter Garden, on its Web site. “You…