Just your imagination fredblue. I've still got the one I bought at Best Buy years ago and one I just received a couple of days ago, and the serpent looks identical.
As a result of my close inspection I noticed one of the new cases has a crack. The jiffy bag strikes again.
Nope, just YMMV (Your Metallica May Vary)..
Look at the pix.. the dupes I had were exactly the same = lighter & clearer front art on the later issue, darker and murky-er-er-er front art on the first release.
anyhoo, I'll pick up another copy in time, this one's common as muck and take some comparison shots of my own!