Backing a horse past a spook?

My horse sometimes has issues leading on a trail ride, and sometimes he will just stop, out of nowhere. I've never really had problems with him not walking past a spook, but i do back him when he gets stubborn and wont walk forward. That is what i have always been told to do, because it gets their mind off of whatever it is that's bothering them. And i believe it is a good strategy that works. It is certainly better than letting the horse get his/her own way!