I know we've become generally smarter over the years, but people weren't dumb back then, surely people noticed : and ; look like eyes, and ) looks like a smile from the very beginning of standardized punctuation...
EDIT: that said, I was probably wrong with most of what I said. There's been typographical variants of 'faces' since 1881 or so: http://en.wikipedia.org/wiki/Smiley#Typographical_smileys But note how these differ a lot from what we are 'used' to. And I still doubt they'd been used in that way anyway.