Why do women jugde you for flirting with older women?

So, it happened with me before and happened again yesterday. I was at the gym and flirted with the secretary, nothing too agressive, and she was not uncomfortable, whom was probably in her early 50's. Even though I probably woudn't date her, I was practioning my game. So I look around and see a lot of young girls staring mad at me. why is that?