Save Draft button posts instead of saving?

I had a post half written out, hit 'Save Draft' while I went and dealt with something and then finished typing it up and hit 'Post'. TO my surprise I found that I now had two posts with the same subject line. Thinking I had maybe double-clicked the post button I went and requested the top one be removed as a duplicate. I now realize that the one I requested was the full post and the remaining one was my draft :p

I've updated the remaining post but it seemed like an odd issue to get. Anyone else experiencing this?