Just to reiterate based on what you mentioned in the ticket, it's possible you were editing a template pre-style property modification and then when you saved it, it maintained the style properties from within the template.
If I understand correctly, it happened to me once a long time ago when I had a template opened to edit and the style properties group opened as well. What ever is saved last defines the properties. Since then I either have a template opened (because it may include the associated css templates), or the style properties group. It hasn't happened since,