Johnny has mentally blocked the letter E

With Johnny starting preschool this year I have been trying to be more dutiful with my teaching skills. I was so good with Alex and she really excelled. I know it really didn't have much to do with me because she has always loved learning but I'm sure it didn't hurt that I always read her ABC books and we always sang the song over and over and practiced counting all of the time. I think we did it a lot though because she liked it. With Johnny it's more of a chore. So every night we have been going over the alphabet and I have been seeing improvements. But no matter how many times we go over it and no matter how many times I enunciate it he always leaves out the letter E. He sings the song "A B C D F & G, etc". So last night I laid out our flash cards from A to G and sang the song with him over and over again. We would take turns saying the letters until he got all of them down except that crazy letter E that apparently doesn't belong. I would point to the letter E and say "this is an E, what is it?" "E" he says. He says E about 20 times then we start at A and by the time we get past the first 4 letters he has already forgotten what letter comes next. What does he have against the wonderful letter E? It starts things like Elmo and Elephant and his best bud Ethan. I've never forced him to eat Eggplant, he does like Eggs and Easter and Exercising. He even likes taking trips to Eureka and loves all forms of Entertainment. I'm baffled. Please Johnny, come to terms with the fact that the letter "E" is a very important part of the English language and I can't do anything to change it.