BEIJING (AP) — Kaillie Humphries crossed the finish line, jumped from her sled and threw an American flag in the air. “U-S-A! U-S-A!” she chanted. Four years ago, nobody would have seen that coming. The former Canadian bobsled heroine is an Olympic gold medalist for the third time — and for the first time, as a U.S. citizen. Humphries is monobob’s first Olympic champion, finishing off a shockingly one-sided competition at the Beijing Games on Monday. She finished four runs in 4 minutes, 19.27 seconds to lead a gold-silver finish for the U.S. women’s program. Elana Meyers Taylor of the U.S. was…