hero levels?

[DragonLynn]

So, what criteria determines what level a hero is when he comes to your town? I just ran into were tigers and lost a couple of heroes - they were level thirty something and the hero that came to replace one of them was level 10. He barely took a breath before he died as well. It is odd because the last time I lost a hero was several levels ago, when my heroes were level 12-15ish and the hero that came in to replace the dead one was level when they arrived. I have never had a hero leave for any reason since the very beginning of the game when they were all level 1. So, is it random what level they arrive at? All the ones at the beginning were level 1. What caused the raise in levels in new arrivals and why did they stop going up?