Maybe just nervous, new sounds, getting used to the leash etc. If you think she is bothered by loud noises, take her when it's a bit quieter and I took mine out in the car to get used to traffic noises.
Good luck with her. :-)
Yes, its normal for a pup to be a little anxious when experiencing anything new. My best advice is to just distract the pup with play etc, and at all costs avoid "comforting " pup. dogs dont understand the concept of reassurance, and if you pet or fuss the dog when it is crying it teaches pup to think there is something to fear. Carry on enjoying your walks!