Sounds like a replication of a previous comment. As noted there, I assume this reflects a high false alarm rate of the current stable release of dcm2niix. These warnings are resolved in the current development branch. So your options are
- Ignore, assuming your data was not acquired with Siemens in-built motion correction (moco).
- Update your dcm2niix to the development branch.
It is always challenging reverse-engineering proprietary formats like the Siemens CSA header. I have never used Siemens in-built MoCo for my own data as I think it is probably a good idea to have accurate measures of head position as nuisance regressors for subsequent analyses. My handling of the MoCo slice times is a direct translation of the comments I received from Siemens engineers, and I have never validated them. If a user does decide to acquire MoCo data, they should understand this is an edge case where very little validation has been conducted.