I received a small meyer lemon tree for my birthday this year.
We've had it indoors, and it doesn't like that--it's been dropping leaves and looking unhappy.
I've read up on this, and the word is: if the branches look healthy and green, don't worry about it.
But of course, I worry nevertheless.
A small note to myself--
Remember: making leaves is Spring work.
Winter is the time to withdraw resources
underground: grow roots, be dormant.
Good advice for all of us.