Well, I'm sure that is the case, but since the pretrib theory sprang from dispensationalism, and it part and parcel with the dispensational views on Israel and the church, why one who is not dispensational would adopt such a theory is puzzling to me.
There is no reason to believe in the pretrib rapture unless one assumes the basic tenets of dispensationalism. You might not adopt all the details in the Wikipedia article, but if you accept the basics then you are dispensational.
Pretrib is a basic, along with the radial distinction between Israel and the church. Whether there are 2 or 7 or 10 dispensations is less material.
"There is no reason to believe in the pretrib rapture unless one assumes the basic tenets of dispensationalism"
Are you then saying the Donald G. Barnhouse was a Dispensationalist because he believed in a pretrib rapture and yet affirmed Reformed doctrine?