I'm probably twisting the rules a bit, but here goes. "The grid can be any shape". Well, my grid is a torus! (And it kinda looks like a swastika, but let's ignore that.)
C+A D 1 + D1+1B + 1 B C+A
The labels are shown twice to indicate where the grid "wraps around". The grid itself uses 11 squares.
I realize that this probably isn't what is intended, but I thought of this and decided to post it while working on a "real" answer.
Pre-edit answer:
How about this:
1A1 !D B !1C1
The space in the middle is a "hole". If A has a mine, then B and D do not, which means that C does. Similarly, if A does not have a mine, then B and D do, so C does not. Thus, this satisfies all three conditions.
It uses a 3x3 grid, with a total of 8 squares.