The most recent nightly builds of Reason contain a resolution to bug #80. All modules should now be able to register their last maintained date/time with the maintained module after the init phase, and, as long as modules are run before the maintained modules, they can even now report their last updated date/time after their run phase (this is a little more iffy, as it relies on modules being run in a consistent order.)
In layman's language: before this fix, some modules, even when they attempted to report when they were last modified, the page footer did not properly reflect that. With this fix, the page footer should now properly report on all modules' last modified times.