Landing in CLT last Sunday on the redeye from LAX, the pilot announced that due to some type of special landing we could not have any electronics on at all, even in airplane mode. They repeated this a few times, how they ensured compliance I have no idea. I can't recall ever hearing this, he mentioned the type of landing it was but I don't remember - maybe "outbound" or something?

It was rainy with low cloud cover, but as far as I know otherwise unremarkable.

What could be the story behind that?