I think that's related to the one I pointed out at the steam forums. Stars with deviating features will be "corrected" once you load a saved simulation.
It appears the stars get all their features recalculated based on their mass and as if they were main sequence stars.
Extremely heavy ones will go supernova, extremely dense ones will get their radius increased to the point they become "normal" stars and so on.
I think the Seed value of the save doesn't include all features of a star, just like it doesn't hold all features of planets for now.
But there seems to be more about it, having to do with realistic mode for stars. As someone pointed out, saved sims always load with stars set to realistic mode, even if you load it paused. The strange thing is that it also happens to stars taken from the original add list, even if they are there in realistic mode already.
I've put up a few screens on steam to show what I mean:
http://steamcommunity.com/profiles/76561197996774227/screenshots/And explained my observations at the steam forums:
http://steamcommunity.com/app/230290/discussions/1/520518053445010176/Don't mind the forum issue mentioned there, since that was obviously solved. Thanks again for that.