Bright child can't retain letter names?

She is still in the learning stage. My biggest concern is that she can't remember it even a few seconds later. I am trying to work with her more at home. Her preschool teacher had not noticed a problem until I brought it up a few weeks ago. She has since been watching more closely and working with M more. The teacher does seem a bit concerned now, and is trying to work with us. I will check out the Leap Frog sustem. Thanks!