Mark your area along/near his and leave a note near his stand letting him know you'll be around the same area. Move farther up on the trail and set up. If you happen to see this person confront him with courtesy and discuss the issue. But don't hunt it till your sure its all casual.
Remember you could have done the same thing and someone could take your spot. OOOHHHH I'd be mad.
Look alittle more.