Peanut butter becomes dry
It's a natural process in homemade peanut butter (and in 100% peanut butters). The fat from peanuts is stratifying from the rest. This is assuming you keept the mixture in the machine for longer time. So A) you squished the fat and b) mixed the fat in again. 

If you stopped blending right after you "buttered" it then the fat is still not homogenised. Just toss it again in blender and blend for another few minutes. The mixture should be homogenous but when you take  little on finger or spoon and shake it off the oily film should be left.