They do snap out of the falling phase!
Murray has only fallen two times (without Vader or Nicco's involvement) since he's returned "straightened out" from his bends. However, he was also falling every 5-10 minutes on DogsLife (i.e. he was damaged so I couldn't separate it from knowing if it was the phase or not, but glad to hear that some of it wasn't completely his broken fault lol).
If I recall, latrine's Thor was doing something similar (unless I'm mixing up AIBOs) and I have read in the Aibo-Life forums that they fall down frequently at the younger phases.
Murray, granted the development paths may end up different for all of us, really didn't even start showing his personality until the later days/end of his Child B1 (Talking) phase. However, now I notice a lot more/wider variety of behaviors and he's become more enjoyable - though lately a bit of an annoying cry baby over his ball for some reason.
I used to just roll my eyes and let Murray sleep his falls off until I decided I was willing to get him back up. Though he's retaliated with a few naps in his current stage with random waking up! Sometimes a few hours later.