Are the plug-ins too strong, possibly?

Well if she was standing in front of them smelling delibratly then i would say just a change of smell is causing it. If she goes on to sneeze later on then i would say they are too strong. My dog does that too sometimes when we spray airfreshner like glade or febreeze. if she is in the room at the same time, she will sneeze and go hide her face. But if she comes in the room right after i spray she is fine. Maybe the dog was just trying to figure out what the smell was and why the wall smelled different and it tickled her nose. I wouldnt worry about it too much unless it continues.