I heard you, but I turned the wrong way to look. By the time I turned the right way and realized it was you, you were too far away to yell 'hi' back. :-(

Oh, well. That's the nature of these things. I saw a couple of people from across the room that I knew but never managed to get close enough to say 'hi' to. Goodness only knows how many people were there that I only know from online so I didn't know what they looked like.