My wife and I have just recently got our third dog, a mini schnauzer from a reputable breeder. We've had her for two weeks now, we also have a 4 year old schnauzer mix and a 7 year old lab mix. Things had been going well until the past couple of days, it started with my wife and happened again with me last night. The puppy has an extreme energy playtime around 6 to 8 where she just wants to run and play hard. Around 8 she will just lay down and she's done for the night. Two days ago she did all this and laid down and after a few minutes my wife went to pick her up and the pup growled and snapped at her, enough to scare my wife. The same thing happened again last night when I tried to pick her up. She's only 5 lbs but it's a little startling to have a puppy act fierce like that.
I'm worried that we've already done something wrong in these first two weeks. We had already decided to enroll her in a training class when she was older, and now we are thinking of doing it sooner. Any suggestions or information is very much appreciated, I've owned 5 dogs and have never seen this before so I'm at a loss as to what I should or shouldn't be doing to correct this.