Trackpad click/Button not always working?

Just bought my MBA about a month ago. Recently it started doing something weird, mostly on the dock icons.

Sometimes when I go to click on an icon, it doesn't do anything, regardless of whether I am clicking, double clicking, or pushing the button below the trackpad. I end up having to move the cursor off of the icon and back on once or twice before it will let me click.

What would be the cause of this?

Thanks!