What you did is the definition of blocking the box - stopping in the intersection (even if your light is green). Blocking traffic would be if your light was red.
It's better this way that the law penalizes what you can control (your own vehicle movement) as opposed to what you can't (the cars in front of you)
i got a fine in London for doing this by mistake. i didn’t even block traffic, i just went into the intersection without the cars in front moving. bam, fine. lesson learned.