if you're doing short sleeves, just move your art 'out' or 'up' on the screen so that the hem of the sleeve doesn't hit the lever area.. you'll likely have a hard time getting a small over the platen mounting bracket and arm.
but I also agree with FarmBoy.... you can certainly adjust the levers a bit... I had to do that to tighten a few of ours that got loose over time. nice thing too is that it helps not catch the really small shirts as well.