This is my first post on your community, but i'm not a complete LaTEX newbie. Writing my thesis i noticed that sometimes after a braces instead of a fullstop a strange symbol appears:

Then, when i compile the document, the fullstop is at his place.
This is therefore not a problem, but I've looked around for the meaning of this symbol, but i couldn't find anything. Does anybody know what does this means?
Thank you
bye