candukid A Stainless Steel insert should NOT be magnetic
iirc, there are several grades of stainless steel. Only the top grades are not magnetic. Plus, not all magnets are equal. Most stainless we are in daily contact with is magnetic. Plus, even some of the non-magnetic can become magnetic over time/conditions.
Your SS iron heads are supposed to be non. But if you have heated them for shaft pulling, they can become slightly magnetic. Again, it takes strong magnets to detect.