The actual hourly dress code says that only associates who regularly go outside (ie door greeters and lawn & garden) and also associates who spend time in the coolers for their job code (ie dairy and fozen associates) can wear outerwear inside.
Anyway, it's not a mandated CHANGE perse but rather an already-in-place rule that wasn't being enforced it sounds like. So it sounds to me anyway like your store manager has policy on his/her side.
It's never fun to make a change when policies that weren't enforced suddenly are but I guess if we err on the side of policy then we won't get our feathers ruffled when management actually starts enforcing.