"O is for octopus, or ox, or uh-oh"

I taught Liam the letter O, not intentionally, but as we were adding the magnetic alphabet to our fridge (every house has to have them, right?) I held the O up to my mouth and said, "ohhhhh." He then wanted the letter O and he copied me and had the letter up to his mouth, keeping his lips in an O shape. The next morning, kinda for fun, I asked Liam to go find me the O. He went from the living room, into the kitchen and pulled the purple O from the fridge and brought it to me. He had it up to his mouth and was saying "ohhhhh" just like the day before. Now he can find the letter O anywhere, but my attempts to teach him any other letter have failed miserably. I guess he is not the savant that I thought he was!!