Need to force close the "Phone" (Dialer) app manually

I have LG E612 (Jelly bean 4.1.2). My problem is, my **phone (dialer) app** will not close automatically when I press "**Back**" from dialer to Home screen. Phone app is still running in background, and I need to close it through a task killer. Is this a normal behavior with all android phones? If not, is there any settings for this?