Yeah, our 16 lb cat tackles the less than 3 lb. babies all the time. It's always good to keep an eye on things of course, but I DOUBT that it would be "bats on the head" like you described making the pup act that way.
My puppy is a HUGE baby....she acts so big and tough, and then the first little thing she doesn't like, she throws a pitiful whining fit. One morning she was acting so spastic, like she couldn't walk, and I was seriously on the verge of throwing her in the car and rushing to the vet. Then I discovered it was all over a little flea biting her on the bum.
This is all not to minimize your concerns! If she is still showing signs of imbalance, of course, that's to be taken seriously! Good luck!