When new cabin crew would come for a flight deck visit I would stress that if they noticed anything unusual they should report it. It would most likely turn out to be unimportant but once in a while it would be something we would really like to know. We would much rather it was reported than not.
Usual offenders were squeaky door seals (would disappear as we climbed) and buzzing lights.
Although there is a story that a cabin crew member once reported the wings being different colours from each other after anti-icing fluid applied…..