Subs as in a type of sandwich are also known as hoagies, grinders, or heroes in the US. The name varies by region; the size and contents of the sandwich by the 'shop.' Hmm, funny name for store, but then I am from New England where we like to buy our grinders mostly from pizza joints.
Most of the regional names date back at least to the forties, so for some of us, they are not new. Unless we move somewhere and they have another name. ;-)
Very much a regionalism, as in New England we have our soda in a bag when we purchase it; midwest and farther out you have to settle for your "pop in a bag" which suggests to a Yankee that his father is inebriated.