Thank u both for the comments !! I did not saw any nasties on the under or upper sides of the damaged leaves, I usually dont have damage spotting mites on the under sides of the leaves of plants, but if its thrips and they are sooooo small I may have missed them.
I checked the damage caused by thrips on citrus on the web, and it seems that damaged leaves on citrus have white/ yellow stripes on them, and other damage like dots and stuff. Her citrus leaves were looking nice and all ,other that they were a little deformed and more thin and elongated.
Hers case may be not as severe as others so I will gust say to her to buy a insecticide and spray .
One interesting thing is that she has her citrus ,lemon ,mandarin and orange all staying together and they are touching each other with branches ,the mandarin does not have any damage, only the lemon and the orange have it. The mandarin is staying between the two others .