That very well could be the case. There is a big difference between "popping" and "clicking. If it were arcing, you would more than likely be able to smell it up close and personal like.
Hopefully getting that saw dust out of there will resolve any chance of arcing.
If you have a multi stage converter, it's very possible it might just be "stepping" as you mentioned. If you're running your furnace, it may be originating from there as well.
If it's been ongoing for three weeks with no adverse affects, I would be less concerned. I would do some due diligence in trying to track it down, but I wouldn't stress over it.