Hello Cash
Unfortunately, it seems to be fairly common now for assessments to take place up to a year before the end of an award. It isn't just you that has come up against this.
I shouldn't be concerned, any more than you would be had your award come its natural end.
You can ask why your assessment is early, but to be honest I think it would be a waste of time. Just complete the form, send as much supporting evidence as you have and wait and see what happens next. I very much doubt that your neighbour, however grumpy, will have had anything to do with this!!
Good luck with the reassessment.