It's not FSRealistic! I was completely wrong!
The issue is back, with or without FSRealistic.
I think it is related to clouds and wind layers, but once the trouble starts, and I remove any type of weather, the rolling continues. I have to end the flight and start another one again without any kind of weather in order to fly without the issue (but I'm not completely sure, I have to do more testing!).
Furthermore, I think, as I thought at first, it's a bug from the last beta update.