Pink tip anemone concerns

I've recently bought a pink tip anemone and he's done alot of moving among the rock and sand, he attached as soon as he was introduced in the tank. But he occasionally retracts all the way up to the size of a bouncy ball even all of his tentacles.Even sometimes when he shrinks up his tentacles skrink to the size of string almost.then slowly open back up over the course of two or so hours. Just concerned over the new tank addition and looking for more experienced opinions. So far I've fed him some little chopped up pieces of shrimp through a turkey baster about once a week just gently sprayed toward his tentacles and he catches them and instantly starts to eat them.also his tentacles have seem to get a hint of light to dark brown in them darker as it gets toward the pink tips. Does he sounds like he's doing alright so far? Just concerned about how he shrivels up about 2 times a day