I've noticed that when someone posts a string of several smilies in a row, like grouphug grouphug grouphug grouphug grouphug or
dancingchilli dancingchilli dancingchilli dancingchilli dancingchilli (I'm leaving out the :: on purpose)...

... the first few will display normally but eventually one will have an extra space in it like this: :danc ingchilli: so only the text will appear. Let's try it:

It just happened for me. The extra space in the fourth chili gets inserted by the software between composing and previewing. As far as I can determine, it does that to any long string of characters without a space:

anylongstringofcharacterswithoutaspaceanylongstringofcharacterswithoutaspace

The workaround? Just add a space after each chili or other smiley: