Not sure where it would go. I took my pre-reqs for my masters after I got my bachelors but I was registered as a non-degree grad student when doing so. So even though I was taking undergrad classes I think it will count toward my post-bacc. GPA because I was registered as a grad student. So I think it depends on your registration status.....but again I'm not sure.
It will most likely go towards your under-grad because you didnt seek a graduate degree. The advisers here at Temple told me that if I were to do a Post-Bac that you get a Post-Bac grade on your transcript but it goes towards your undergrad GPA because it's not considered a grad program. However, if you do a SMP (small masters program) that will cause you now to have a graduate GPA.