ok, well that is a good idle temp, yah i figured it was stock cooling.
I would keep it at where it is right now, cause 10 minutes at 100% load is a lot of use, you will never have your 100% usage of you cpu , unless you are doing a test like this,i think you are fine, that is about the same time i did mine for, i think i did mine for 15 minutes, and it went to 60c, so i mean, after a while it stays the same temp, i think your good, but i would recommend you gettin an after market cooler, or if you don't want to spend the money atleast get some new thermal compound, if you get some artic5 it could lower you temp by 6c, which then it would put you in the zone you would like to be.And thats like 5 bucks.
If you are going to get an after market cooler look into this.
http://www.newegg.com/Product/Product.aspx?Item=N82E16835233003