Signs of a slow thaw in the jumbo mortgage market are lifting the spirits of some Charlotte-area mortgage lenders. With prospects for an economic recovery slowly improving, Wells Fargo & Co. recently decided to expand a jumbo mortgage program that had been limited to its retail customers. The San Francisco-based bank is now funding some jumbo loans for mortgage brokers and purchasing jumbos from other mortgage lenders. “We’ve reached a comfort level with that product,” Wells Fargo spokesman Tom Goyda says of the decision to add more jumbo loans to the bank’s portfolio.