Most top 40 stations have a standard playlist that gets updated every so often. They don't play anything else. When they are doing their listener's choice, call and ask for a song even from 6 months ago. They will probably tell you they can't and ask you to suggest one of the current songs, so they can record it and play it 2 weeks later.
It's part of the illusion of radio, it's really fake radio. Why they seemed to have that song cued up as soon as that the girl asked for it. Wow.
I listen to talk radio in the morning and on the way home. If I want to listen to music I listen to my ipod or one of the alternative stations.
The station you listen to is the typical Z Morning Zoo, popular teenage bop music. Turn off the radio, listen to your cds or switch it to a less ridiculous station.