I saw that too , but to tell the truth , his health is full.
So this is how it goes :
Russell has 800 hp in the mission (I guess by his default stats) which is set by lua in that mission for some reason (I guess , remember I am just trying to logicly realise how this happends) but Russell in my mod has 5000 so the game just keeps that Russell can have up to 5000 hp but it makes it 800 , so it shows you that Russell has 800 hp out of max of 5000.
If Russell was regenerating health you could see his health would fill slowly and then it will be full (5000 hp). I am not going to make Russell Regenerate cuz he is strong enough with 5000 hp thats a TON.
Anyway , Thanks for all who have reported , please keep reporting before the 3.1V will be released in a day or 2.