Phone volume changes

What happens to the volume when you are listening to the iPod? Also, try using the earbuds and see if it still acts the same.

Dave M.
MacOSG Founder/Ambassador  An Apple User Group 
Creator of 'Mac611 - Mobile Mac Support' (designed exclusively for an iPhone/iPod touch)

Well there are not any volume controls on the screen while in a call, so cannot see how any screen touches would do this (plus screen should turn off while next to ear while on a call).

I will assume you are not touching the volumn on the side.

If you can repeat this consistantly, I would make an appt at Apple Store (call 1-800-MY-IPHONE first) to show them. However, I would say first do a restore because that is going to be the first thing they will want you to try, so get that out of the way. If they witness the problem and there is no physical damage to the phone caused by a drop, they should replace it on the spot.

Ok another question for you. When in a call and you bring the phone to ear, does the screen turn off as it should? Or does it stay on?

Well there is more than just an earpiece up there. There are sensors under the glass for light, proximity, etc.
The plasic that it shipped with was for packaging and not the type of plastic one would keep for screen protection and provide all the proper input still. Best if you did remove it. If you want screen protection, you can buy one made for that sort of thing.