Spells: AoE targeting ...a bug?

[Mayge]

I thought that the AoEspells that target 4 mobs will first target whatever mob you have targetted for the spell and then the next closest 3 will get hit. i have seen many times where the one.(say there was a group of 5 packed up tight, insteadof hitting the one you have targetted it seems kinda random who it hits... that doesnt seeem rightbut not sure its a bug.