BB Curve :: 9300 Manual Network Selection?

when i set my curve 9300 to manual network selection, and i select my networ, if i go in a palce underground or something and i lose the signal, the phone doesn' t pick up the signal automatically when i am back in a coverage area. instead, i find an alert window that says "can't find home network and asks me to chose whether i waast to: set it to automatic, go into settings, or cancel" and i have to either go in settings and select it again or jsut set it to automatic and it will find it. in other smart phones it usually gives that alert, but as soon as i am back in a coverage area, it picks up the home network on its own without having to go to settings. so is this the normal behavior?