Steps on A models tend to fail
I know of several RV-xA that have had their steps crack. The crack usually forms in the thin-wall tube a little way out from the weld. An improvement would be to put a doubler on the tube at the base.
Anyway, its a chore to drill out two handfuls of rivets to remove the step to re-weld it. Some posts have shown ideas for making the area a bit more accessible for service.
Bottom line: step gingerly on the step, no bouncing up and down, and it will probably be fine, even at your weight. An impulsive step can easily put 1.5 x weight on the step, and that's probably what is cracking them.