The gig is you cannot get disability payments AND drill pay the same days, or something similar.

I was labeled 20% disabled when I retired. The stipend was small, but appreciated anyway. Several times during my 7 years in the ANG I got a note from VA saying they had overpaid me, and would therefore reduce/suspend future payments until the balance was correct. I never wrote a check back to them or had military pay docked in any way...just reduced the already small benefit to almost nothing for several months.