Buttner made an appearance to see his old teammates in their 0-0 draw with FC Twente.
"With the fans I have always had a good relationship," he said. "I had to leave at 06:00 am to get here, but I did it gladly. I would absolutely come back to thank the fans."
Of his progress at United, Buttner smiled: "I've played more than I expected. It's really surprised me.
"But I also was surprised when I did well at Vitesse."