I've been nipped dozens of times. Never had any more than a localized infection similar to what I'd get from any scratch or scrape. Soap & water then neosporin.
I've been bitten twice. One just had minor localized infection (age 5, hunting dog bit me behind the knee) and a little minor tendon damage. One had me in the hospital for 11 days (age 11, doberman leapt for my face but got my arm). Gangrene was only one of the many infections that spread from wrist to shoulder. Multiple surgeries to try and clean out the infection and save my arm. (successful, btw). And multiple surgeries to repair the muscle and tendon damage. The doberman belonged to friends of ours, was very healthy, was current on all of it's shots... but dog mouths are filthy. C'mon people... they lick their own bums and eat carrion (rotting foods rife with microbes and parasites). Things that would never make a dog sick CAN AND DO make us very very ill. This case sounds extremely superficial, but with my bite it was irrigated for over 2 hours and I still got a massive local and systemic infection from the bacteria in the dog's mouth.
My son's been nipped twice. Both times just localized infection similar to any scratch.
If any redness develops around the mark, take a sharpie and outline it. If it grows, take her in. If it stays the same, and she has no other symptoms (fever, etc.), no worries.