They let you take a 16 oz container of liquid through security? Or you bought it once through security and they let you on the plane. If it's the former, you got MAJORLY lucky. It's not supposed to happen.
And it's so funny b/c this thread was made the day after hubby took a flight where his bottle of water, which he got from the United fancy-pants lounge (he'd been upgraded to 1st class so he got to hang out there that day), was NOT allowed on the plane. They had secondary security checks at the gate, and he was told he had to leave it.
Now, this was coming from Peru, but still, he's been allowed to carry water onto the plane, after buying it in the airport, all over the world, but not on that day on that flight, for whatever reason!