Chaos: As you don't have a recon, you won't know this, and Sandoz might have opted to barricade his hq with 2 bombs and dispensed with the 3s! :)
But yes, you are right, I ought to replace it with a 5.

Perhaps a minimum of 5 movable pieces must be chosen, and a general cannot be selected unless you have the one below it. So if you went for 5 pieces, you could choose 1x1, 1x2, 1x3, 1x4, 1x5, or perhaps 1xRecon, 1x1, 1x2, 1x3, 1x4 or even 1xRecon, 1xSab, 1x1, 1x2, 1x3.