I suppose it depends how the system is designed.

If it works in "real-time", then yes our reputation counts would rise and fall as grey boxes convert to green/red and then back again.

If it is a "one-time" change, then once you're point level reaches or surpasses 20, then a sweep is made that converts all greys to the appropriate green or red, as necessary.

I guess it depends on what the system is designed to do, or what back-end programming might be required to implement it.

I'll just keep making sure I note why I gave reputation so the recipient knows what I intended when my point total is lower then 20.