It sounds to me like there's more to your story. There had to be some reason for you to have had a stress test. Just passing one of those means you can walk across the parking lot, but you didn't just walk in and ask for one.
A very short increase in heart rate only a couple of times probably won't get your cardiologist all excited, but if you get these a lot he might want to have you wear a monitor. If youhaven't told him about it though, you might want to.
Maybe you were working out unusually hard, Maybe you ate or drank something unusual. If this keep up you should be keeping a journal so you can figure out when it happens and what you are doing to trigger it.