That's how Silas counts. We didn't even know he could say his numbers till he filled some in recently when David was counting. He liked our reaction and is now proud to do it regularly.
He also knows you point to a group of things (for instance, dots) when you do it, though I don't think he is actually counting.
He can also sing the ABC song all the way through (including an easily understandable "Now I know my ABC's, next time won't you sing with me"), even though his biggest sentences so far have probably been things like "More dookie right now".
Maybe it's time to teach him some Mekons songs.