My girl would growl when approached when we first brought her home, but that stopped after a few weeks, so it may not be a permanent behavior. They are just not used to being bothered.
We have had her almost a year and she still likes a little something extra in her food. EVERY TIME. And, (haha, not that she is spoiled or anything!) she likes it to vary. You can't just pick something and add it every time. Cheese one day, chicken another, sometimes broth will do it, sometimes I just have to add a treat to her bowl and she will eat the treat and then everything else.