Hi Stan
Yes and no to your question
The fact that you don't get the wave centered, is due to your audio card. It's something that happens, and the more professional and expensive the card, the less the DC offset (btw, that's what it is called) becomes.
To rectify this problem is as following:
#1 - Once completed with your recording, goto noise reduction (in CEP) and take the noise sample.
#2 - Apply the noise reduction to the whole song, and you will see that your DC offset is now zero!
Hope that helps.