Starbucks is blaming "congestion" for its disappointing sales growth. The Associated Press reports that CEO Howard Schultz said the chain's popular mobile order-and-pay option has prompted "bottlenecks in the areas where people collect their drinks." Additionally, Schultz said the issue has "created anxiety" among some customers. Starbucks' U.S. sales rose 3 percent at established stores for the three months ending Jan. 1, but that is attributed to people spending more money each visit, not new customers.