I don't use steam but that's partially just because I can't ever seem to remember to stop myself from "ironing" rather than "pressing", so I have issues with distorting my blocks ANYWAY. Steam just makes it worse!
I even put a label on my iron that says "PRESS! PRESS!" and that doesn't help. Of course I put it on the handle so I can't see it when I'm holding it, maybe I need to put it along the front and sides where I can actually see it when I'm ironing....PRESSING! lol