drush: How to upgrade to a stable module release instead of dev?
pm-updatecode (and pm-update, which calls it) will not ever switch from dev to stable.  If you're on a dev branch, and want to go to a stable release, use pm-download.  For example:

drush pm-download somemodule-7.x-1.2


OR

drush pm-download --select somemodule


Make sure that the stable release is newer than the dev release you are running, and then run drush updatedb.