Yep, she is starting her adolescent period! It seems that right after their terrible twos they are great for a month of two and then go right into adolesence! Here is an article about puppy adolesence:
http://www.peninsulahumanesociety.or.../article5.html
My favorite part of the article:
"most dogs exhibit at least some of these common adolescent traits: selective hearing; refusal to do previously learned commands; reversion to puppy behaviors such as mouthiness, destructive chewing, jumping and barking; lapses in housebreaking and just about anything else to drive their guardian insane. The good news is that this period in a dog's life doesn't last long; the bad news is that it isn't short enough."
The article gives several helpful ideas to survive this time in your puppy's life. Good luck!
P.S. my baby just turned 7 months and now has "forgotten" every command I taught her!