(Reuters) – Brisk back-to-school shopping benefited many U.S. retailers in September, with strong sales growth at chains from Kohl's Corp to Nordstrom Inc suggesting optimism for the holiday season. Shoppers largely brushed off the prolonged economic malaise and the U.S. East Coast's recovery after Hurricane Irene. Chains with fresh items enticed shoppers while others were left to question their strategies heading into the critical winter holiday shopping season. Overall, 23 U.S. retailers posted an average sales gain of 5.1 percent at stores open at least a year, or same-store sales, according to Thomson Reuters. "I'm not saying it's going to be going to an exceptional or a blow-away holiday, but I wonder if people are being overly pessimistic," Madison Riley, managing director for retail...