This is wrong, it just takes so little valor that if you level up in a pvp match the valor from that match carries over. Until about valor rank 45 it takes no more then 2 wins to gain a rank of valor.
That kinda answers that.... I guess I never noticed how easy valor is to get. Seemed a little excessive to level and instantly be half way into my next level. It only seemed logical that it was stacking. Of course with how much PvP I do I've never paid that much attention to it at higher levels. Pretty much stays maxed.