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The leaf likely brushed against a paper bag, or something else, and had a little mechanical damage. It is nothing to worry about.
Phals like yours, in sphagnum moss, need to get almost dry between waterings. The roots turn white when dry. Yours are still green, so it doesn't need watering right now. Some people would repot now, but if you are careful not to water too much, it will be fine in that moss until the moss starts to break down.
Here are two good threads to read on growing Phalaenopsis:
Using skewers to determine when to water
The Phal abuse ends here.