Canadian-born curler Erin McInrue Savage understands her sport isn’t the most popular of athletic endeavors in the U.S. But she doesn’t think she should have to make the case that curling is a sport at all. Yet that’s what Savage, a researcher on aging, said she was forced to do last Sunday when an American Airlines employee at Phoenix’s Sky Harbor International Airport allegedly balked at allowing her to check her curling broom as sporting equipment. “[The agent] said curling isn’t a sport,” McInrue Savage, 34, said Saturday, a day after posting her exchange in a post that went viral on Facebook.