Yes, it is. When a man undergoes vasectomy, sperms do not vanish immediately from his ejaculate. It requires time, between 3 to 6 months or over, until the sperm count diminishes to zero and no sperm are found in the seminal ducts after various ejaculations. Throughout this timeframe, it is possible for the man to have cryptozoospermia.
If you liked this story, you may want to go through this: Post Vasectomy Semen Analysis – How Many Tests to Confirm Sterility?
Suggested for you: Cryptozoospermia – Definition, Causes, Treatment & Pregnancy.