The bar is clamped in a metal vise, so the vise is very slightly heated and that side of the bar is much cooler.
Taken using the Topdon Android attachment.
Does this also affect bandsaws, with a single, thin blade that moves rapidly? Your assumption was always mine until I saw this photo, and thought about it. Chances are the replaceable blade was the motivator, and heat dissipation was a happy side-effect.