What is the appropriate age for the "Warrior" series by Erin Hunter. Is 8 too young?

My 8 year old son, just devoured the first three books within a few days, and I have not had a chance to read them myself or review them on line extensively. I heard they involve murder? lovers? All in the feline world, but still...Any thoughts? I would describe my son as intellectually above his grade level (has been TAGged) but socially immature. We don't watch much television and I err on the protective side...I try not to be too helicopterish, but am.