I'm rather new at citrus (only a year or so) so please take my comments with a grain of salt.
Based on the temps you're talking about, I wouldn't be worrying about the roots being too cold. My Meyer lemon continued flowering throughout the winter inside and my house was seldom above 60 degrees - and probably colder near the window where it was located. Once the daytime temps got above 63, my Kaffir lime broke dormancy and started growing / flowering.

I'd guess that the leaf loss is more due to the disturbance of repotting but from what I read a little leaf loss on a Meyer is totally normal and since yours is putting out new growth I'd guess you're ok.

The soil just isnt drying the way I want, even though its very well draining. It just feels cool to the touch. I worry more about root rot, with moderately cool soil. I have a ton of new growth on all trees, in the 2 ish weeks I have had them, 1 tree has a 2nd small flush starting. Another, is putting out water spouts like mad... so at least its happy! Trimmed them back and it seems like new growth on them like mad. All are in full out flush right now. I love seeing all the amazing new growth. Shows I am doing something right.

hey, I wouldn't sweat it at all!

You are getting much better growth than I because your temps by day are keeping the roots to your trees much warmer than mine without the sleeping blanket.

Becareful not to over heat the roots too and cause leaf drop.
Your plants by nature should cool off at night, not below 50-55 and warm by day. This will cause great growth which is what you are seeing. I wouldn't change a thing with all that light.

It is true that Meyer Lemons notoriously drop leaves if light can't penetrate the middle, causing the lower leaves to fall, transplant shock, or extreme light and temp changes. But from the sounds of it, I'd be happy with what they are doing compared to mine.

Keep up the good work and Makalu, great advice.

By the way, are your trees nice and rich green>?

Mike

The Meyer I repotted is having a few of the lower leaves yellow... my guess due to the repotting, not a fert issue. Other than that, they are an amazing dark green. I am very happy with them, but the leaves turning yellow... even if partially expected... scares me.