MBP "Clicking" When Screen Saver Starts/Stops

[clayj]

Has anyone seen this?: 15.4" MBP from April 2006... starting today, when the screen saver starts or stops, or when I first turn the machine, there's a very faint <click> sound that comes from the screen. It almost seems like there's an issue with the MBP's backlight changing brightness modes. I think this started happening right after I installed the new Security Update (2006-008?).

Any ideas or experience with similar issues?

EDIT: Well, as mysteriously as it started, it has now STOPPED clicking when the screen saver engages/disengages. Weird.