I think it's just an implementation bug or design bug, like the darn "…" text clipping of titles and episode names, losing its place when you hit the Back button or return to the car, and the offset scrubbing bar (see below). But they're too busy adding games to fix these bugs. At least they fixed the album art display.
For a while I had trouble scrubbing (adjusting the position) of audio played from a USB drive. Today I discovered that if you tap and slide ON the line, it doesn't work. You must tap ABOVE the line, as demonstrated here: