Hard to say without a picture.

I just added the image!

Some where along the line it was hit with frost without you knowing it, that is what I think.

New lemon foliage growth can look purplish if it's exposed to high intensity light; as the leaves expand and mature, they produce more of the other chlorophyll pigments and green up. The flowers do the same thing; they can look purplish if exposed to strong light but would otherwise appear white growing in less light.

Tom, what she was saying is that the new growth is very fragile and tear. My new growth does not do that. It should still be strong even if it's new. That is why I am saying this never gets below 40 might be something he/she is not aware of. Happened to one of mine and the new growth did just that. Could be wrong though. Just a guess) That bud is very brown looking dead on top.

By the way Tom, hope you are well these days)

Oh I missed the bottom line... yeah, it might have cold damage. On clear nights, things at the surface can get a lot colder than ambient air with low dew points. It's really prevalent out here in CO--for example, the air temperature was 41*F, but there was already ice forming in a water tray I had left out!

What can you do about it at this point? Nothing. The tree will either decide to keep flushing despite the damage or just abort the shoots.

And Mike, glad to see you're still here! You're a pillar in this community. I'm doing well; I moved to CO for work from NE in October of last year, and it's a bit different here for growing conditions!