I "think" :
1. The cold dry the salad
2. Condiment the salad in an error. The oil becomes solid and ruin the salad.
3. The salad may take odours and tastes from the rest of the refrigerator when is not closed or protected.
4. A salad with a canned sardine in oil is an error. A sardine must not be put in the refrigerator for several reason with the salad. Probably will past the flavour, odour and taste to the rest of the dish.
5. the salad may be refrigerated without condiments.. (and close for not share odours and flavours).
6. If the salad had fruits like orange, or bananas, or apple is more sensible to look old or past after several hours in the refrigerator, specially if is not close the dish or protected by a film. The film protects fresheness.
I wish to comment these points. Then I can present a reclamation to the restaurant....