Yes, that is my assumption, too. But I tried it several times to update the bricklets. It reported the check is ok after upgrade.
I have tried many combinations of bricks (master, dc, servo, all hw 1.0 and FW 1.1.1) and bricklets (piezo, distance, joystick hw 1.0) with no success.
However I received a new order this week with a master brick (hw 1.1 and FW 1.1.1). I then got the piezo bricklet working by upgrading the bricklet FW. It now also works on the older master brick. I'm still stuck with the other bricklets so. Tried the same procedure with the distance bricklet, but this did not work.