Because she’s so perfect she understands it would devastate people to see such perfection, so she shows she has fake minor imperfections strictly for their our.
Dakota was already in the other place, though. How long is the important part. Given the lack of profuse sweating and nail-biting, however, she mustn’t have spent long without phone network.
Except she wished there was air there, not that Phoebe could live without air. This is going to confuse NASA a lot.