Sometimes when i first log in i notice my dinos say they are at half health and little bloody. then after about 5 min they are full health with the health being the lesser number. ie 3500/1750 to start, then down to 1750 after the 5 min. Anyone explain why?

I also noticed that leveling up isn't as big of a jump in stats. sometimes as little as 3% roughly sometimes 4%. Is this a server setting?