Why does %dist evaulate to el6 on a el6_4 system while building an rpm?

Issue

• When an rpm dbus was built from a src rpm dbus-1.2.24-7.el6_3.src.rpm, the release comes as el6 instead of el6_4 which should be the case running el6.4.
• Why does %dist evaulate to el6 on a el6_4 system while building an rpm?

% cat /etc/redhat-release
Red Hat Enterprise Linux Server release 6.4 (Santiago)

%  rpm --showrc | grep dist
-14: dist       .el6