no
you are probably feeding him food that he has never eaten before
hes probably been fed only one type of food his entire life, and here is this new food he is not used to. hes just waiting for his old food
bettas can survive around a week or so without food. just offer it to him daily, and if he doesnt take it after 15 min take it out. he will eventually get so hungry he will eat anything
if you return and get another one the same thing will happen. if its really a huge deal, go to the petstore, ask what they feed their bettas, buy that food and he should eat it.