That's because Uncle Iroh's first voice actor was named "Mako". Sadly, he died during season two, and then Greg Baldwin started voicing after him, hence the memorial message in the episode you mentioned. The character Mako has the voice actor's name as a tribute.
I winced a bit when I heard Dante Basco's voice coming out of this guy, thought it was a little to obvious homage. But in the last couple episodes when he was all "Oops, lost a sleeve because I'm bringing out the gun show...no seriously, shooting down planes over here", they won me back.