They did last year, after the no-more-than-three-ounces-per-container rule came into effect; on the other hand, "they" was Air Canada, and it's possible the US rules are slightly different on this. (The only difference I'm aware of is that if you're flying out of a Canadian airport, the limit is 100 mL or 100 g, which is slightly more than the 3 ounces the US gives you. But I'm no expert on this.)