Is It Normal That the Edges of my Two Front (Rebonded) Teeth Are Stained, Had It Done Well over Ten Years Ago? (photo)

It is normal for bonding to be stained after 10 years of service.  5-7 years is a realistic expectation of the lifespan of bonding.  It will vary from case to case depending on diet, tea, coffee, smoking, red wine, etc.  Having them polished periodically can prolong the lifespan somewhat as well.  Your solution will be to have the bonding replaced or make the switch to porcelain veneers which have the advantage of never staining.