I've heard something similar. I've heard that you're not suppose to have them up past the 2nd of January. WDW better grab a big ol' salt shaker and toss a pinch over whichever park is considered the shoulder.
As I sit here basking in the glow of my beautiful Christmas tree I laugh out loud at the notion of bad luck befalling those slow to put decorations away. :lol:
My family holds the tradition that the decorations should stay up until January 6th (the Epiphany/Little Christmas), and come down promptly afterwards, but I never heard of any bad luck associated with not getting them down at that point!