When I use the color selection on the notes to highlight my resource in different colors, the highlights are gray the next day. I tried resetting the color on some of the notes, and they were gray again the next day.
These 2 passages were highlighted in purple yesterday:

HP Pavilion dv7 Notebook PC, x64-based, AMD Turion X2 Dual-Core Mobile RM-72, MS Windows Vista Home Premium.