Mod quest script not updating when the mod has been updated

[Ep1cL3w7z]

I made a mod called SexLab Nude Werewolves. I released an update that added SexLab Aroused integration. The problem is, the main quest script doesn't seem to have been updated in saved games - when saves are loaded that had the old version of the mod, with the new version active, the update notification doesn't appear ("SexLab Nude Werewolves updated to 1.1"), and the code that enables Aroused integration doesn't seem to run - both of these things are handled in the OnLoadGame method that is called by the PlayerAliasScript.

The only relevant errors I can find in my trace log look like this:

[12/11/2013 - 07:56:08PM] ERROR: Unable to bind script SLNWPlayerAliasScript to SexLabQuestNudeWerewolves (8C000D62) because their base types do not match

When the updated version of the mod is loaded in a brand new save (or the ESP file is renamed), the Aroused integration works perfectly fine.

You can look at the source of both versions of the mod by downloading them from the mod's download page.

I'd appreciate any help.