Uploading of itr by system

yesterday night i was uploading itr 4 in java ,it was showing error response null, then i uninstalled java and installed latest version of java 7 update 60 and did nothing .Now today i saw in my email that return has been sucessfully uploaded. i have seen the itr form in incometaxefiling site all details are proper.now i m confused how it was uploaded i think it was detected by the system automatically and uploaded.Any one has gone through this.

Pls reply.