If you try and over-feed a human what do you think will happen? He will decline eating more food. Correct?
She is a little overweight, she can afford to lose a little weight and as such she is not hungry.
If she becomes bony (under weight) AND is not eating, this is the time you need to start worrying. In your case, there is nothing to worry about.
Addendum
I know some pet owners want to spoil their pets, but I assure you, they are not doing their pets any favours by keeping them overweight. Only yesterday I was watching a program on overweight dogs. The vets were really stressing to dog owners that over feeding an animal is not a good idea. They even had a human being wearing saddle bags and go on a treadmill to demonstrate how damaging it is to have a fat pet. When you have a fat pet, you are essentially shortening its life-span.
When I talk of spoiling my cat I am meaning that I have been to ready to give her something else if she did not fancy what I have put down. I am well aware that this is not the way to go but a sad look a plaintiff meow and I am putty in her paws. I appreciate she is now probably playing me now as she has learnt that she is likely to get something else possibly better if she plays her part well enough.
Time to man up and try and get a more regular meal regime.