Hi, Philipp-
That is odd. Can you check the NIFTI header directly, with:
nifti_tool -disp_hdr -field pixdim -infiles DSET_EPI
Does that show a TR of 1s? That is, is the value of pixdim[4] (zerobased counting) equal to 1.0? Note that first 5 pixdim values are:
pixdim[0] -> flag about qform or sform
pixdim[1-3] -> spatial voxel dims
pixdim[4] -> TR
It is possible that there is a conflict between a stored extension (with 3dinfo would check) and the primary NIFTI header (which nifti_tool will check). So, please let us know about that, and then we can decide best how to address that issue.
--pt