Angle of view
We often talk about how important angle is. In this video below, the referee makes what appears to be a correct PK decision. But notice how his view of the incident was blocked by a player. What if there was an embellishment by the attacker? What if there was more than just a trip to escalate the contact to be reckless? Just because you made a correct decision does not mean your positioning was correct. If you did not have a clear view of the challenge, your correct decision can easily be considered a luck.
Keep adjusting your positioning. Keep your feet moving.