No, there is no fiberglass in dipping tobacco. That rumor came from people seeing the salt crystals in the dip. A can has about 2300mg of salt so it's quite visible.
I've been dipping for two years, know all the risks, but love it too much to quit. The irritated skin is from the high acidity in dip and the actual tobacco is what damages the skin. Combined with the high levels of acid it feels like your lip is being cut but thats just anti-tobacco propaganda.
I suggest using pouches more often and put the occasional cut dip it, that'll really reduce damage to your lip but you'll still get the wrinkles from the salt drawing water from the skin.