In adults patients is it normal after palate expansion to have the palate start to narrow or go back as teeth and bite are aligned and corrected?

Palatal expansion is usually accomplished on young adults before the mid palatal suture fuses. As the palate is expanded and then fixated, bone fills into the space that was created. The same would be true for adults. This should prevent relapse but there are no guarantees.

You list your age as 57. It is impossible to successfully complete palatal expansion in a 57 year old without orthographic surgery. Isn your were "treated" with "palatal expansion" without surgery, I would suggest getting a second opinion from both qualified Orthodontist and Oral Surgeon.