I don't know if this has been asked already...

Just came to ask that very question myself, I don't see any references at all to it and I saw the movie twice. If I had to guess, my guess is that it's a clue to the 3rd movie but I don't know if the 3rd will happen since the movie didn't make as much money as Sony originally wanted (but they say that was due to too many PG rated movies being released at that time) and the fact that the actor who portrayed Papa Smurf died (though it could be possible for them to just hire another actor who sounds similar).