Something odd just happened

I had a saved scene with four characters in it. The size of the saved scene was 2M. I accidentally deleted one of the characters. No big deal, right? I just hit the un-do button. But something strange happened. A dialogue box came up saying that the hair was not for this character and that the hair needed to be auto fitted to the character. Which was odd because that didn't happen when I first added the hair.
What happened next was even stranger. When I went to save the scene, the size it took was 35M! I deleted the hair off the character completely and loaded it up fresh and saved the scene again and it was back down to 2M.
I repeated all of this a second time to see if it was a one time fluke and deleted the character again and brought him back with the un-do and sure enough, the same thing happened.Has anyone ever experienced this before and does anyone know why it's happening?
I don't need a solution because I figured out how to fix it but I'm sure curious what is going on and why. This did not happen with the other three characters in the scene because I experimented with deleting them and bringing them back and there was no issue.
Comments
It is one of the many mysteries of Daz Studio, I have issues at times when I load a scene and get ID errors.. Yet if I load the same item in a new scene have no problems at all..
I think once you delete something, it is stored in a temporary file so you can undo so it is not actually reloaded from your library but that file.
So you actually have a huge cache of temporary data associated with it
The file size blow-out is probably down to auto-fit as the hair was considered not for the character. Auto-fit changes the geometry of the item fitted, and this is stored in your main saved file, which can increase the size of the saved file.
Hairs need a character in the scene to be fitted correctly so if that character dissapears and returns the hair might not work properly or recognise the link to that character. A stab in the dark.. but maybe.