It is very rare to see a manager doing this, it just shows that you care about the participants of your campaign and want them to improve, Im hoping they will improve and stay longer in your campaign.
I've seen a couple of instances where a manager will post on the spread sheet week after week phrases such as "low post count" or "improve the quality of your posts" or similar, and those warnings go unheeded, then when they are dropped decry they weren't warned.
Haha that has happened in a lot of my campaigns for a lot of different participants.. Oh well!