I have a 4 month old lab puppy. This is new territory of me, I have never owned a lab or had a dog I needed to train. She recently lunged at me without warning (she was laying on the sofa and I was standing up) and she almost bit my face. She was really showing her teeth and it completely freaked me out. One minute she was laying around chewing on her toy (no I didn't try to take it from her) and the next she was trying to bite. I have a small mixed breed dog and she doesn't like my lab so if they are in the same room (which is only in the mornings) she might growl and snarl at my lab or even try to bite. I'm wondering if my small dog's bad behavior could be rubbing off on my lab? I have a big yard and I take her out and walk her around multiple times a day. I don't let her run off leash because the last time I did she lunged at me and bit me.
I recommend training classes for both your puppy and older dog. And in the meantime, no couch for the puppy... and up the exercise outside. The toy guarding inside was no good, but the "lunging" at you outside could have been in over excitement. If you're really concerned, contact a behaviorist to come over and see the situation first hand.