Essence Reaver Problems?

I've noticed that the amount of cdr that I get from Essence Reaver is off. Earlier today it was the first full item I built and for some reason I had 20% cdr instead of the initial 10%. I didn't have any critical chance items to contribute to ER's passive and I didn't have blue buff on me. The cdr I got from the item in the end was still a max of 30%. Am I missing something? Or is there a problem with the item that I haven't heard of?