It rained like a monsoon, Jennifer McManus of Coldwell Banker Realty, remembers of a recent weekend when she held an open house at a property in Maplewood. At one point, she had to go out to the street and clear leaves from a storm drain so the debris didn’t cause flooding. The homeowners were out of town. Before they even got any offers, the sellers asked if they could increase McManus’ commission. “I’ve never had anybody do that before,” she said. It paid off. The house, listed for $729,000 on March 6, closed on April 16 for $1.139 million. That’s $410,000 (56%) above asking price. The sale …