At each node of a plant stem is a structure we call a leaf when it's fairly large, and a bract when it's a lot smaller than a leaf. Most of the time on Phalaenopsis flowering stems the nodes are subtended by a bract. In this case the bract has enlarged to something between a leaf and a bract.
It might happen again, and it might not. It doesn't affect the plant otherwise.
A keiki growing on the flowering stem will make a rosette of leaves and later roots.
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