Rear diff metal shards/splinters??

[ScottyBoy]

I recently had to redo my rear diff gasket because it was leaking. 90% of the oil had leaked out because the bolts on the cover worked their way loose. As I was removing the cover, I found that all the bolts were barely hand tight. I remember torquing them down when I changed the gasket last, which was actually only a few months ago, it was in February. When I changed the oil in February, I didn't notice anything out of the ordinary as far as metal shards. I just saw a good bit of the metal particles that look like metal dust or more like mud. But this time there were a few small chunks of actual metal. Nothing huge, but big enough to be very noticeable. The biggest chunks were about the size of a grain of rice.
Now here is a bit of a back story: A few years ago the spider gears in my rear diff stripped out and ended up causing a good bit of damage. I had a shop replace the spider gears, but they didn't do a full rebuild on the differential. They just "flushed" all the metal out with some solvent and they claimed it was good. I then had them replace the diff cover gasket about a month after the repair as it was leaking all over my driveway. I'm not sure how much metal was in the oil that time, but I am guessing that it at least removed some more particles since the gear oil was replaced yet again. So what I'm getting at, is should I be very concerned about this? Or is it possible that I'm still getting old metal debris from the spider gears getting flushed out? This will be the third time the oil has been changed since the spider gears were replaced.