iTunes cover flow mis-match betwn Macbk pro & ipod

I have approx 300 albums on my Mac, synced with a 160GB ipod classic. Using "cover flow" on the ipod, it matches very well for the first 250 albums or so -- by author, then title. But the final ones are then apparently random by author / title. I've checked the "info" and that seems fine, author in the right slot etc. Any ideas?