Type B Washington found in Phila Mint Set

[GKoehl]

I have four 1964 mint sets and of those I found one whiich has an estimated MS70 type B reverse; the other three and the Denver did not have a type B.

Can anyone tell me if there is any significane to this? Is the situation similar to that of the missing dime in proof sets?

I can dream can't I??????

thanks