The sliding in and out of the tub vs the open door/top of a tank can sometimes make a difference, too. I doubt the entire cage slid around every time you checked on the snakes before this, so the movement can make a difference.

Give them some time and let them settle in, and definitely like everyone else suggested try switching the bedding back. The sliding of the tub plus a substrate that provides no resistance like they're accustomed to may be throwing them off.

-Jen