yes, that is perfectly normal for an anemone of any/all types.
As Toffee said, it is simply having a poo.
even though some anemones can survive on light/algae, all are carnivores and can eat the same meaty foods you feed the fish. Every week I target feed my condy's and next day they are doing the exact same thing you describe.
It's kinda nasty looking, but nothing to be concerned about.
all anemones go through cycles of deflating and inflating, some many times a day.
if the mouth stays open and they look deflated for a prolonged time or can't attach to something, then you may have issues.
in the event things go south, always siphon out a dead/dying anemone, never try to remove it any other way, it can get very messy and smells like death x 1000.