Increased Aggression in my Older Lab

Question
My 11 year old male lab has always been very sweet and still is most of the time.  Since about 2 years ago, however, something seems to trigger anger and aggression.  He unexpectedly bit my hand one day when I was removing his dog food bowl to clean it (there was no food left in it).  During a dog park visit a big great dane puppy kept trying to play with him, until my lab bit the great dane. My lab has always been wonderful in the park before, never showing signs of aggression. Then about 6 months ago my grandson tried to hug my lab after his companion dog died and the lab turned around and again bit him.  He no longer will share his water bowl either without growling.  It this just a change in behavior due to old age?

Answer
As dogs age their senses diminish just like people, he seems to have problems with both handling and his food/water bowls. Geriatric onset aggression is most always a medical problem. I suggest a senior wellness profile (including blood chemistries) to see if there is anything that need addressing.