Bug in Guitar Hero World Tour, GH5 causes score to roll backwards for Wii drummers

It's tough enough to earn a good score playing Guitar Hero World Tour.  But for drummers on Nintendo Wii, hitting the notes correctly might earn you a worse score than missing them. How can that be?

According to the #1 drummer on Wii Guitar Hero World Tour (ranked by overall career drum score as of 08/31/09 on the official GuitarHero.com Leaderboards), "Koric" claims that a bug in the drum rolls (long notes) sometimes causes the score to drop upon completing the roll.

Indeed, he has posted a video on YouTube proving this is exactly the case.  Watch as he plays "Sweet Home Alabama" and his score goes in reverse by 5400 points.  Start around the 6:00 mark, he goes into a drum roll and finishes with 580K, but after the note ends, the score reverses to 578K.  Then he does another drum roll and finishes at 582K only for it to reverse again and drop back to 577K, shortchanging him by at least 7500 points:

Koric says it's not just Sweet Home Alabama, but other songs with long drum rolls where the game's score malfunctions.  He notes that during a past game he lost 12,000 points due to the same error.

Normally in every Guitar Hero game ever made, the score is a one-way number that increases, but never decreases.

For a game centered on progressing towards earning high scores, issues like these are both disappointing and worrisome.

Update: Guitar Hero 5 Reportedly Has the Same Bug (09/16/09)

GH5 drum player "firescull537SH" reports that on his Xbox 360, Guitar Hero 5 exhibits this exact same bug on the song "Scatterbrain":

As I was working on my scatterbrain score today, I noticed that something odd was happening after the hold not on the green/yellow (or yellow/orange for GHset users). Also note that I didn't miss in the intro hi-hat stuff during any of these runs. So the glitch is that after the hold note, my score would drop by 2k. Seriously. I would start the roll at ~28k, see my score rise up to ~30k, then the moment it ended i would be back to ~28k. At one point I tried not hitting the green for a second so I wouldn't be getting as many points, but I stopped for a short enough time that i would still get above 30k. When I did this, my score only dropped down to ~29k.

I'm seriously confused here, and I held the note to the end every time (as in i wouldn't stop rolling on the pads until literally 1/4 second before it ended at minimum).

I'm on the 360, and it's only happening on Scatterbrain.