weird thing?

[alsakari]

I came across something in a battle last night,I don't know if it's a bug or not.I had 51 R. snakes and some marauders.Used sacrifice on marauders and increase snakes to 54.I lost 2 snakes but the game didn't allow me to ressurect them(had L2 res).So I finished the battle with 52 snakes.
Battle results screen:casualties 0.
Repeat the battle did same thing,only now I allow to loose more snakes so that to have below 51.When I try to ressurect,the game allow me to ressurect as many snakes as to reach the 51 original number.
I'm rather new to the game so is this a game aspect?