I am also seeing this occur - when I have applied a perspective warp to a smart object then turn the perspective warp off, it does not 'unadjust' the mask, it remains. Then when I turn the perspective warp back on, it skews the mask (if linked). This seems odd since it ends up skewing the mask only when turning the already defined smart filter ON, but not adjusting when turning it off. The skewing that occurs (if repeated) will continue to move the mask away from the object being masked.
Unfortunately, I can't reproduce this offhand. Can you make a sample PSD (and share via Creative Cloud or dropbox) and provide steps to reproduce the issue? If I can repro, I can log a bug with the team to try and fix it.