Thats fairly warm for idle temps on a stock dual core. For example, my 50% overclocked quad core idles around 30C on all 4 cores and i have a LOT of voltage going through it. Make sure that all 4 of the click posts are actually clicked in all the way. I know when i had the stock cooler on mine, it was a giant pain to get them all in right, if 1 isnt fully latched, it could be causing you to have temp issues.
FWIW, my e2180 idles at 20/20.