She may have had a full bladder and then got overly excited and lost control, or it may have even been submissive urination too. Tommy used to have a real problem with that when he was younger. My husband would come home and reach down to pet him and he'd just go off like a sprinkler. . The best thing to do if that is the case is when she is overly excited, to just ignore her until she settles down somewhere, then call her over for calm praise and attention. With Tommy, I also started anticipating events that triggered his submissive urination such as my husband getting home from work and take him out to potty before he got home. It's important that if she does lose control, you try to have as little reaction as possible. I'd just calmly lead her outside or to a kennel and then clean it up, no scolding or excitement over it that might make her more anxious.

I agree that it's not in retaliation, dogs' minds don't work the way a person's does in that way. If it's a territorial or dominance issue, some basic obedience can help, and I'd highly suggest some of the books out there on positive training methods and dealing with dogs who are confused about their place in the pack. A lot of those things can also help with an overly anxious/excitable or submissive dog too. Of course bladder infections or medical causes should always be ruled out too if it becomes more commonplace. Hope some of these thoughts may help