And everyone else has been pointing out that the 100ml/3.4oz container standard is routinely applied day in and day out across the world, including within and from the USA. It is difficult to tell a 4oz bottle from a 3.4oz bottle visually unless you read the writing on it, but sooner or later a security operative somewhere was going to do that, and you were going to lose the bottle. The regulations relate to the container size not the amount of liquid in it, part-full bottles have to comply with the size regulations.
Why not name and shame the US company who sells something as suitable for air travel when it has been against TSA regulations since the day the liquid restrictions started? Unless of course they meant it was a convenient size to pack in your hold baggage?
It is convenient for travellers if security everywhere checks the exact same things each time, but it is also convenient for terrorists since once they've found a way of getting explosive or weapons on board, they know it will work. By varying unpredictably which items they check in detail, airport security tries to make it more difficult for would be belt bombers, mix-on-board liquid bombers, carriers of exploding i-Pads and so on, without the whole air transport system grinding to a halt because every single item is completely checked everywhere every day.