They have a puzzle category the 60s or in the 60s. When the first showed the puzzle they showed the old puzzle board from another episode. Did someone run the wrong tape?
In all seriousness, GiraffeBoy is right. Pat explicitly stated that they intentionally "recycled" puzzles on April 6 for Going Green Week, and they acknowledged the fact by showing a clip from an older episode on each puzzle reveal.
I find it interesting that they used The 60's, even if only for one episode. I haven't seen any of the "decade" categories in about five years, and even when I got back into the habit of watching in 2001, I don't remember seeing anything older than The 70's.
It still could've been much worse. They could've brought back Megaword. Or Foreign Phrase. Or Slang.