Chalking It Up To Experience Graphic artist Sean McDonough, a 34-year-old Canadian citizen, doesn't seem like a security threat. He's polite, soft-spoken, clean-shaven, and owns a one-bedroom condo in an exclusive downtown Toronto neighborhood. But on Wednesday night, when McDonough arrived by Greyhound bus at the Buffalo, N.Y., Peace Bridge border checkpoint – on his way to participate in Sunday's Kennedy Center Open House Arts Festival – he was denied entry and sent packing back to Toronto. "Everybody got off the bus and went into the waiting area. I was pretty well held over while everybody else was allowed to go ahead," McDonough told us yesterday, a couple of hours before making his second attempt to cross the border in order to take part in Edwin Fontanez's Washington Chalk Festival, a Kennedy Center tradition. "I answered a lot of questions. I showed them my sketchbook. When I said I was going down for a chalk drawing festival, the lady got very suspicious. She said, 'Are you going to sell any of your art?' And I said no. She said, 'How do I know that?' And I said, 'I guess you'll have to take my word for it.' And so they rejected me." We tried to obtain an explanation from the appropriate federal officials. McDonough said he noticed the blue uniforms and sidearms of U.S. Customs officers, but a Customs Service spokesman sent us to the Immigration and Naturalization Service. The INS told us Customs was responsible. "He's an artist: If he says they were wearing blue uniforms, that's good enough for me," an INS public affairs officer said. But then Customs insisted that INS did the deed. "This is not the first time that Customs has bounced something back to us," the INS flack responded. But later we were told, confidentially, that the INS had filed an incident report describing its role. Department of Homeland Security, anyone?