Rube showed up where I was. He didn't have the bit in the menu that says he's there for someone else, so he was definitely there for me. I tried to talk to him, but he didn't react to the menu choice for the twenty times I tried. It closed the menu each time and he kept walking around. After his song ended, he hung out for 3 or 4 minutes, then finally poofed. Made me think he was making offers which weren't showing up in the game window. Other people reported the same thing earlier.
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Saw him twice more. One time he wasn't looking for me. The other time was for me and had the same result as above.