Are you still taking Molly out on seperate walks of her own too? If so does she still bark when people are approaching, or is it only when Honey is with you?
I think you have hit the nail on the head, it may be jealousy or just the pure fact that she is not used to people approaching all the time.
Firstly make a fuss of her yourself everytime someone stops you, and don't be afraid to also ask people to fuss Molly too. She may even be being protective of Honey and not liking all the attention and is warning others of her presence.
Don't worry, if she is anything like my dogs soon she will become bored of all the attention Honey gets and just plod off when people are cooing over her and best of all Honey will soon grow and loose the publics interest and that should really settle her back down again.