I'm not familiar with your particular model, but if it's a single piston caliper, the piston will probably pop out, just as you said.
However, a little lubrication on the sliders might solve your problem.
If the calipers aren't leaking, you probably don't need to rebuild the caliper and it wouldn't help anyway. Your issue is the lateral sliding of the caplier and it sticking instead of sliding.
Wire brish & lube. "Never sieze" for lube between two cast iron parts or silicone grease if it slides on pins. :p
Slick,