No..Pretty common for Meyer with lower light levels, lack of fresh air, dry heat in a home if warm, and just a fussy plant.

If you start seeing twig die back, then I would be concerned. That spells over watering or a very poor mix for this time of the year.

Also, pest's can be destroyed if this is the cause. Have you checked?

Mike

thanks so much. I will give it a squirt of insecticidal soap as I do see two stringy threads hanging on it. No twig die-back as yet.

I can't add anything to what Mike wrote, but I will recommend that you shoot on over to the Citrus Forum.
If you post pics, diagnosis will be much easier.

Josh

My key lime is prone to really massive/total leaf loss in the winter. Put it back outside in the summer and it's fine.

I think it's a mixture of already less-than-optimal indoor lighting being worsened by shorter daylight.

Also watering is sort of tricky to get right in the winter too. There's no active growth, so I tend to underwater. Except sometimes I underwater too much and that also makes the plant shatter, so whatever.

and yes from what I've heard Meyer Lemons are the worst citrus in terms of spontaneous defoliation.