Capt Wally, I have several thousand hours on the Classic 747 but have never seen this kind of damage before. What you suggest is possible however. The panel may have suffered FOD on the previous landing and was missed after flap retraction but could have caused it to jam on subsequent extension.
ACMS, you are right the colours don't look like QF but Cathay do not operate the 74 into Sydney other than Cargo and they certainly weren't involved.