Has anyone gotten pregnant after a vasectomy?

Yes, but the chances are very slim. Vasectomies are the most reliable method of family planning with a failure rate of less than 1 per thousand. The most common reasons for failure are a) that the man didn't wait long enough after the operation (usually 2-3 weeks or 20 ejaculations) before having sex, and b) that the vas deferens spontaneously reconnected. The chances of a failure after properly clearing and being tested at 3 months are put at about 1 in 4000, or 0.025%.