I've been using Feliway plug-ins for several years with no problems. I did have the one that felt hot to the touch a couple of months ago that I mentioned in the other thread but I believe that plug-in may have been my first one that was several years old. I think you would be fine with a new one. Even if it helps I still wouldn't feel safe leaving them together with no one to check on them. Feliway only helps so much.