Reply by LesB

Check out this posting about a “safe” push stick. https://www.lumberjocks.com/topics/308922

Another thing Kelly left out above is that your were cutting with a box joint blade which is wider than a normal saw blade and has fewer teeth which only increases the chance of problems developing. It might have been a good idea to make the cut in a couple of passes to get to full depth.

-- Les B, Oregon