Lucky and Peppa were great at putting themselves to bed when they were too pooped to play on daddy or had enough daddy snuggles, they'd look at their bed-tub, and when I finally took the hint and placed it on the lounge next to me on the coffee table, they'd crawl across and into it and disappear inside their little hide.
George does something similar when he's had enough floor time, he'll crawl over to his tank and look at it then at me, and repeat this until I take the hint and lift him in.
Puff did the same and now Toothless is doing the same thing.
Not trained them to do this, this is self taught by them..... Lizards are much smarter than most think.