Abnormal file name (wc1meanu*.nii)

Hello,

I'm checking through the functional (rsfMRI) files generated during preprocessing and found for one of the subjects the wc1art_mean_au*.nii file was names differently (as "wc1meanu*.nii"). Same issue repeated for wc2art_mean_au*.nii and wc3art_mean_au*.nii for the same person. Could this be a simple glitch in naming? The brain image itself looks similar to other normally named images.

Thanks in advance for anyone's attention.