My cat's behavior has changed a little, should I worry?

My 7 year old female tabby has recently begun acting a little differently. It's not a significant change, it appears to be attention seeking. Last night she sat on my bed and cried. Even after being fed, she just cried. I would pet her, and she kept pushing her head into my hand much more than usual. I wondered if maybe she had a headache or earache. I felt her all over to see if she would shy away from a painful spot, but she didn't, I looked in her mouth at all her teeth and ran my fingers over her gums and she didn't react like any of the teeth felt painful, her teeth and ears look good. She is overweight, being a lazy indoor cat, but she is eating and using the box normally, she has always drank a good amount of water so that hasn't changed, and she's not losing any weight. There are no other symptoms. I was planning on taking a wait and see approach and just give her a little more attention, but when I pulled out her favorite toy for a play session today, she wouldn't play. She wasn't interested at all. She still gets excited about treats and still cuddles, she's not hiding or doing anything that indicates to me that she's sick or in pain, there's just this small change in her behavior and I don't know whether to worry about it or chalk it up to her not being in the mood to play and wanting more attention. I can't afford a vet visit (my father just died) so I will take her if there is honestly something to be worried about, but I just don't know.