Letters "o" and "e"

Yesterday morning I walked in to get William out of his crib, and I had a shirt on that said "Memory Walk '04." He looked at my shirt and pointed to the the letter "o" and said "oh" (he also pointed to the zero and said "oh"...but I will give him that one), and then he pointed to the letter "e" and said "eee." Did that really just happen or was I dreaming. I continued to test him through out the day, and he really does know those letters. The funny thing is I have no idea where he learned it. We just bought an alphabet puzzle a few weeks ago and have not done much with it. I am betting that his amazing babysitter Miss Angie, must be teaching the boys the alphabet....I am AMAZED!