phalaenopsis with soft yellow stains on leaves

[RosieC]

It does look like it could either be sunburn or an infection of some sort.

Keep a close eye on the patches, if they spread at all I would remove the damaged portion of the leaf imediately to stop it taking over the whole plant. Dab cinammon spike on the cut edges of the leaves to stop further infection.

If they don't spread they are probably sunburn. You said that it was in bright light. Phals like bright but indirect light, if they are in direct sunlight they can easily burn.