That's what I am hoping other people will kick in with too. Because she has bitten, I would definitely want to look at the behavior closely.
When I got my GSD at 8 months she did the excitement chatter. Her sister, who I fostered years later, does a snappa snappa. My dog "grew out" of the behavior as she got less nervous, more confident (3 years of obedience classes). I have not seen her do it in forever. With her, it was just a matter of getting comfortable, feeling protected, not feeling she had to do anything, and leashing/tethering to me to reinforce that feeling of "oh, she's got it."
Her sister, when I first got her, did it all the time, and I didn't even realize how much until she almost snappa snapped my face at the vet office and they all went EEEEEEEEEEEEEEE and I didn't know why!
As time went by, she did it much less, but she was about 9 when I started fostering, and it was pretty ingrained. She still does it in her new home. With her I tried replacement behaviors to give her something else to do, strict boundaries/NILIF. She also needs tethering in new situations/with new people to keep her on the straight and narrow.
ETA - Castlemaid made me think - say on the off chance it were excitement and happiness - I would still tether her and use a tug or ball to keep her mouth occupado
with you, not the guests engaging her.