Possessive Basset Hound

So my sweet 9 month old male basset has recently started to display some behavior that is bizarre and a little unnerving to me. Up until now, our trips to the dog park have been wonderful... he'd play with all the dogs, visit all the people, and mooch all the treats he could. However, for the last two weeks or so, he has begun to show a little aggressive behavior. For instance, whenever he sees me petting another dog, he will stop whatever he is doing, run up to me and the other dog and proceed to growl and snap at the dog, chasing them away. He does this over and over. It's as if he does not want anyone else getting my attention. He is also getting possessive over treats. If I, or anyone, am giving him treats and another dog comes up for a treat, Noba will snap at them and chase them away... even if I am the one that called the other dog over to me. He snapped at the cat the other day (got in trouble for this one), because I was eating dinner and tried to give the cat a piece of chicken. Noba did not like that one bit. I was at a friend's house with Noba the other day and he consistently snapped and growled at all three of the other dogs that were around (they are all under a year of age)... this just does not seem like typical behavior for a basset hound and after the incident with the cat, I am a little nervous about it. Has anyone had any problems like this with their pet or can someone point me in the right direction as to what may be causing this? Could I be spending too much time with him, spoiling him too much? Thanks.