Thanks Rick. Looks like my data wasn't resampled after all.
What I was looking at earlier was through "Define datamode ->Misc -> Olay Info" from the AFNI GUI and that showed "outfile" dimensions as 1.00x1.00x1.00. I assumed that this called 3dinfo to display this information and it probably does. What I didn't realize was that my GUI was set to ACPC view. Converting to ACPC is probably what creates the resampling. Switching it back to Orig view set it back to the original voxel dimensions.
Running 3dinfo explicitly from command line shows the original data dimensions as 3.75x3.75x6.00 which seems right.
Thanks again - I'm a newbie and still learning the inner workings of AFNI :).
