I'm not sure if this is a native issue or a plug-in problem, but in V6.2, ticket Notes are shown with a grey background. This hides the text for the ticket time and date, which are also in grey. You can see the time and date on ticket comments, as they appear on a white background. And if you highlight the "hidden" text, you can read it as it shows up in white. It does not affect the name of the person who entered the note, as that text is in black.
We are running V6.2.00901.