Hello,
My normally sweet and docile lab mix growled at me tonight!

He jumped on the couch next to me while I was watching TV. I guess I leaned my head in too close when I was hugging/petting him because he suddenly growled/snapped/barked in the general direction of my face.

He has done this once or twice before, mostly when you touch a certain part of his back leg, but this time it startled me because he was right in my face.

This dog does not have a problem when you clip his nails, pick him up etc. He often rolls over on his back when you pet him so you can scratch his belly. Also, he is neutered, crate trained and not destructive. In general he is a good dog.

But what is up with this behavior? Is this an indicator of worse things to come? Is it perhaps because he sat on the couch with me and therefore thinks he is "in charge?" (He does not sleep in our bed by the way).

Thanks!

The first thing I would do is have a vet look at that leg. If he is sensitive to having it touched, there is a physical problem that needs corrected.

However that is no excuse for aggressive behavior. The dogs see all the
People and dogs in the household as a pack with each having their own rank in
The pack and a top dog. Life is much easier if the 2 legged pack members
Outrank the 4 legged ones. You can learn to play the role of top dog by
Reading some books or going to a good obedience class. A good obedience class
Or book is about you being top dog, not about rewarding standard commands with
A treat. Start at http://www.dogsbestfriend.com/. You are correct that letting the dog sleep with you can lead the dog to thinking it is top dog. So can letting it up on the furniture, but I wouldn't banish him to the floor yet.

If you rub his belly when he comes and rolls over demanding it, he is in charge. If you roll him over, and rub his belly when you feel like it, you are in charge. You need to learn the top dog stuff, going through doorways first, he moves out of your way, you eat first, etc.

Hi,
As the other answer said, your dog thinks he is the pack leader, or the Boss.
You have to show him you are boss, and you can't be "afraid" or "nervous" when you do.
Look sternly at him, put you fingers firmly (don't hit him) on him, and roll him over on his side, massaging him gently. If you show the least little bit of fear or nervousness, he will know it.
The classes are a good idea, because they will show you about being the Boss in your own home. Dogs can train us, to get whatever they want, and to act the way they want to. It has to be reversed, with You telling him what to do, and showing him that you are in charge.
Aggressive behavior is normal and natural, and has to be reverted back to you, in charge.
A very, very, very good example of this is the TV show on NGEO channel. If you get this TV Channel, please watch "The Dog Whisperer". It is a great show, and most of the episodes deal with Aggressiveness. It will be well worth your time to watch a couple of them, and certainly will show you what needs to be done.
I mention this particular TV show cause it's the only channel we get with this type of good information.
I do wish you the very best, and good luck with him.