I don't see it as a problem, even long term. I think children are allowed to seek comfort when they need it from their parents.
The only thing I would say is that because this isn't normal behavior, and started recently, you should have a talk with them about why they are feeling the need to sleep with you now. It could be an underlying issue or it could be that they are experiencing stressors in life they aren't able to cope with.
Either way, talking to them about it would be the best idea.
I generally try to default to neutral terms. There is no need to get this triggered over my choice to use neutral pronouns.