Bad Dog! - or Playing?

Today, when I was out having lunch with friends Craig, Jim and Jeff- and Tom was home gardening and doing house repairs, our weimaraner and dachshund were sitting peacefully on the lawn with Tom for a long time. At one point an older woman and her husband walked by with their small dog-and our Weimaraner ran at them barking and jumped on the woman scaring the heck out of her (bringing her to tears, I'm told). I wasn't home unfortunately and heard about it from Tom. Luckily, our neighbor who is a county police officer was outside putting things in his car and grabbed our Weimaraner who was barking at their little dog.
Was it dislike or play? - After all, our dog plays with other dogs at day care all the time, and she's passive, not agressive, and is a submissive dog, not a dominant dog.
Why does our Weimaraner not like little dogs? One reason is that this past winter, Tom's sister brought her little Yorkie over during the holidays. Our Weimaraner, who always loved every dog, was trying to play with the little Yorkie, who in turn, bit our weim through her nose causing it to bleed a lot (it's the most painful and sensitive area on a dog). Since then, our weim hates little dogs other than our dachshund. So, trauma will even affect dogs.
In fact, whenever we walk the dogs in the neighborhood, our Weimaraner barks at some of the little dogs (usually the white furry ones, which is odd because the Yorkie that bit her isn't white). So last night while walking her past a fenced in yard with a dog she barks at, I had a bag of treats with me that I let her sniff before getting to the fence. She barked once and I told her sternly "NO!" I commanded her to "WALK" and put the treat in front of her nose and led her past the other dog behind the fence barking like crazy- but our dog marched on and didn't bark. She IS very obedient (been to school a year for it), and got her treat in the end. I felt badly for the older woman, but our police officer neighbor was outside, and calmed her, and there were no injuries from the jumping, thankfully.