This your first "plated" weapon?
If you mean you can see small spots where the nickel plating has rubbed off of the rails where the slide and rails rub together then, yeah, that's normal. You'll see it on any plated gun in areas subject to heavy wear. (Even hard chrome.) You'll see similar wear abrading the finish on any gun, in that area. There's a lot of force and a lot of abrasion at play in that area, and you're going to see some wear, no matter what.
If you mean larger areas of the finish are peeling off on the outside of the gun, then no, that's not normal, and the base metal probably wasn't prepared properly prior to plating.
If you've gotten Hoppe's #9 (or similar copper solvents) on the slide or rails, you might be making matters worse, too, as many finishes are applied over copper.
(This is true with nickel, and generally true with hard chrome, too, which is applied over nickel, which was first plated over copper -- as neither of those finishes stick to carbon steel without help.)
Hoppe's attacks copper, and if there's any break in the finish (as might be the case with areas of heavy rubbing/wear) then the copper remover will remove the underlayer, causing the finish to go south, too.