Goldendoodle puppy - 11 weeks - with Lip sore - ulcer

[Galina]

I hope you can help! I have a puppy that is on its way to come Sunday, but was told the vet found small sore (ulcer,) on its lip. They think its from play with other puppies, and have given her a shot of antibiotic. I'm reading that things can be much more serious then they are leading me to believe. Is this fairly common or should I be worried?