Release builds are shown in a job's build history with a box icon next to them making it nice and easy to come back to the job and navigate straight to something you released. However, if you a) perform lots of subsequent builds or b) leave the job idle for a period of time, the build history will churn and the release build will eventually drop off the bottom of the history. I think it would be a nice improvement if the last release build were kept in the build history, at least until another release build was performed.