I have a 14" Delta BS with a riser block. I was cutting with a narrow (1/8" or 3/16") blade and noticed a little "flutter" in the blade. But when I tried increasing the tension a bit, I found that the blade would simply ride down the crown a little (or a lot, depending on the tension increase). The result was that the tension remained essentially the same, as the increase in nominal tension seems to have been offset by the slightly decreased working diameter of the wheels.
Is that normal? It does not happen with the wider blades (3/8") that I usually work with.