Correct ruling?

[MickeyHoldem]

OK... players A & B know each other

Player A (UTG) raises to 15, Player B sitting next to A calls as do 2 others, then I raise to 55 from the button.... the blinds fold... now player A holds his cards out where player B can obviously see them (the entire table sees B look) and looks at B... so now I say to the dealer... "C'mon... B still has cards", B looks down and quickly mucks his cards, but the dealer kills A's hand as well...

Was this the correct ruling... the floor backed the dealer... and A & B left pissed!