Puppy growls when strangers try petting her

[Lauren and Basil]

We took our 4 month old doodle on vacation with us. She enjoyed long days of playing in the water and hiking. Of course every person that sees her wants to run up and pet her. She allows it for a second and then seems to get nervous and lets out a growl and a snap. I'm caught off guard and can't sleep at night thinking about her reaction to multiple people and children. She is surrounded by 6 kids and has never acted like this. I can count 3 instances now when a gentlemen tried petting her she snapped. Multiple children but the one with crutches she snapped at and lastly a group of children she snapped. Most of these instances before I even have a chance to speak people are petting her. I am scared to death now she's going to bite someone. We have been through obedience class and she did great. Again, she is great around our 6 children (ages 2-11). Is this a puppy phase she will grow out of? Any training suggestions? I'm so upset over this. I don't want a dog who can't go into public with our family, or scared when children come over to our home.

[Jane, Guinness and Murphy]

I think everyone has given great advice.  I would add that I also have a fear reactive dog, and we worked with a trainer to desensitize him around many of the situations you describe.  If you know his triggers you can create situations where you expose him in a controlled way and then use lots of positive reinforcement to help him through his fear.  We did lots of these sessions getting him used to the grandkids (and we also trained the kids on how THEY needed to treat Murphy).  Just as an example, we have one grandson who is on crutches.  I pretty much knew that would be a trigger for Murphy, so we introduced him slowly...first at a distance...and then getting closer and when he showed no fear we gave him treats and lots of praise.  After a few times he learned not to be afraid of the crutches.  When you go out in public, keep some good treats in your pocket...expose him slowly to distractions that may cause a fear response...reward when he shows he can be calm around the trigger.  At the first sign that he is anxious remove him and try again in a few minutes or wait for another time.

[Cheryl and Finnegan]

I don't think it's unusual for a dog to get alarmed when a stranger reaches for them.  No one should pet a dog without first asking permission but we all know people do.  I second the idea that training classes continue --at least over the first year because pups not only learn commands but they get exposure to interacting with other owners and dogs through different development stages. It might be fun if you make the CGC a goal to work towards together.  Your pup is just coming out of a normal initial fear period -- 8 to 11 weeks I think.  Crucial to keep training and develop a strong foundation because she will go through a second fear period around 6 months or so.  This might help:

http://ice.ucdavis.edu/~robyn/Korina/BCIdeas/Criticalperiodsinpuppy...

When I was socializing Finn, I used to carry treats and  would sometimes give children a treat to offer him.  He had to sit and then they could give him the treat in a flat hand --then pet him on the shoulder or under the chin.   Initially wary of kids, he learned that these little people could be gentle and "rewarding." Today, we can go into a school and 50 children can pass him in the hall, and each one pats him on the head and it's no big deal.