macbook trackpad uses mouse settings

I temporarily connected a basic three-button mouse on my Macbook (white 2009) running OS X 10.9. In order to make the mouse more responsive, I needed to max out the settings to make the mouse responsive. I then removed the mouse, without restoring the original mouse control panel settings. After removing the mouse, I went back to using the Macbook trackpad. I noticed that trackpad operation was degraded, specifically it didn't recognize double-clock commands anymore. As the trackpad control panel has no double-click setting, I was mystified as to what happened. I plugged the mouse back in again and restored the original settings, removed the mouse, and the trackpad started working properly again. Is this a bug, or what? As the mouse control panel is basically empty when a mouse isn't connected, it seems like the trackpad should use its own settings. But, it obviously is influenced by the mouse settings. Thoughts?