Zygonisia shed leaves?

[snowflake311]

I have had my Zygonisia since Nov 2014. I even got it to rebloom. It has been doing really well for me. It was growing like a weed. I moved it to a colder room under light after the blooms fell. Few months later I had the Old leaves fall off. I have new growth too. I pulled it out of the pot to check for rot. All I saw were Old roots with lots of new healthy roots. SO it is not a rot problem.

Is it good for these plants to shed leaves?

Any other people on here ever experience this leaf shed on Zygonisia? I might do a video on it. and repot it.