Yes, thats normal, its the control channel. If you are trying to monitor one perticular talk group on a trunked system, you must press and hold the trunk button until it beeps while the talk group ID you want to monitor is "talking". This will put you in whats called ID HOLD MODE. You can also lock out all the other talk groups on a trunked system if there is only one TG you want to listen to.
This information is for radio shack scanners only, I do not know how to do it on any other scanner. Although it may be the same.
Sorry for this description, I know its a bit hard to follow. Its late and I'm tired! lol