There is a difference between being grammatically astute and being absolutely fastidious.
Take IGM's post, just above this one:
It took me ages to get it, but once I did
Generally your grammar seems top notch, but Eighthours, Hero of Canton and I (I'm sure there are others) would put a full stop before the emoticon, just because it's proper.
No, no, no. If anything was to be placed before the emoticon it would have been something like a dash or a colon, as it is part of the same sentence. This would have been followed by a full stop. However, I find punctuation after emoticons to look a little ungainly and out of place unless I am continuing to talk (type) immediately after it. I, basically, said (wrote) "It took me ages to get it, but once I did I laughed out loud." so the only thing missing is the unnecessary full stop.
That's my story and I am sticking to it.