Answer: I honestly don't know what it may be - lichen or moss, perhaps? I suggest that you again contact the nursery from which you purchased the tree and ask for more specific information; while it may be "nothing to worry about", it would still be helpful to know what it is! In any case, take photos to document the situation. Usually nurseries offer a 1-yr guarantee on their wares, so if you find that the tree declines despite your following their instructions for planting and care, you have that to fall back on. I also believe it's wise to try and find plant material that is locally grown or offered by a reputable company, and is willing to answer your questions. Good luck!
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