Summer always brings in the AS3 application question it seems.
Honestly, your ambient temperature has a lot to do with the temps. It can have a 5-10C difference sometimes even though your ambient goes up as little as 2-3C. Trust me on that one. Another possibility is that when you measure the temp it's not completely idle yet, maybe it's still recovering. And one more that I can think of, if your temps are increasing after you put the AS3 on instead of decreasing from the "settle-in period" then it must be that fans are failing or you moved your computer around to a LAN party and slightly threw the heatsink off about .25mm or something. It could be a lot of things guys and honestly 46 idle and 58C load isn't bad, it's summer and when it's 90F-100F out there you gotta expect those temps... unless you're rich and have l337 AC.