Seems OK to me.
Radial distortion can have both positive (outward, away from the principal point) and negative (inward) values. Negative radial distortion is denoted as pincushion distortion (since an imaged square will appear to have its sides bow inward), while positive distortion is termed barrel distortion (because straight lines bow outward). Either positive or negative radial distortion may change with image height, and its amount is also affected by the magnification at which the lens is used. It can also occur that one lens system suffers from both negative and positive distortion, like your example.
Cheers, Geert