I would recommend looking at this from their own point of view, and thinking about why they might be asking you this information.
From my own experience at a few companies where actual processes weren't defined well on paper, some managers may simply be trying to figure out where a specific process or action being taken is being defined / where that came from, if they're not familiar with it.
Were it myself, I would first assume my manager was confused on the process that I was following, and would explain to him what I understood to be that process,
and then ask him if he believed there needed to be any changes to that.
If so, take note of what changes need to be made, and then the next time you're asked, your response would be very similar, but with that manager's changes appended and a note that they'd asked for that to change.
If you have a process document somewhere that outlines exactly what was supposed to be done in that scenario, it becomes very easy to simply reference that document as your reason for handling something a specific way.
If you're doing something specifically based on feedback you've received from superiors, just make sure to note that. In what I would assume would be most cases, you're not in trouble.
Don't assume you're in trouble unless someone tells you you've done something wrong, and that you've done it wrong multiple times after being told not to.
Even if somehow you've made a mistake or a bad decision - and i'm not saying you have in this instance - those things happen, and someone would have to think you were doing so repeatedly and not responding to feedback before thinking that there was a serious problem.
So, to conclude, my feedback would be to brush off feelings that a superior is directly upset with you, and instead recognize that the supervisor is just upset, and at the same time, they have to figure out why a specific decision was made.
They might be under stress of their own, they might be facing pressure from other higher ups, and very likely if they're asking you questions about why a decision was made, it could be because they have to report why a decision was made (They'll usually generalize it to avoid pointing any sort of 'blame' on any employees) to their own supervisors, if it's something they're aware of and are wanting a report of.
The best thing I could recommend to you is to make a serious effort not to take something personally unless someone very bluntly makes it personal. It's very easy to mistake one thing for another when it comes to communication in the workplace; in my own situation I either ask someone a question to clarify the situation or brush it off unless there's some kind of evidence that someone's actually upset with me - such as them telling me "Hey X, We're going to need you to do This in the future, instead of what you've done here - as that is an actual request for me to act differently.