I'm just feeling so stressed.

So I just came out of an extremely stressful, 3-hour examination. About two seconds after I closed the door and walked towards the inner part of the building (with the intention of buying a snack from the vending machines), a woman wearing a "volunteer" tag told me, "Why did you do that?" She sounded extremely offended and kind of like she wanted to fight me for some reason, so I remained calm and asked her "What do you mean?" She repeated her statement again, to which I responded the same. After a while of this, she started gesturing towards the door and said, "Why did you exit through that door?"

I exited through that door because the other two exits were blocked by a crowd of administration people as well as more test takers and I didn't feel the need to forgo a perfectly good door in favour of shoving past them. 

But I simply said, "Oh! Was I not supposed to go through that door?" I think I sounded polite, that was my intention anyways. Here's how the conversation went:

Her: There were people behind you.

Me: There was someone behind me -- (was interrupted)

Her: There were people behind you still taking the test. 

Me: Why does me exiting through this door matter to them?

Her: They can see through the door. (She then gestures behind us, where there is an empty staircase and blank wall).

Me: Why would that matter? There's no one near the entrance --

Her: You slammed the door. (Keep in mind that initially she berated me for just exiting through this door). That was extremely inconsiderate.

Me: There was no one near the entrance and why would anyone look behind them during a test? And I didn't slam this door.

Her: That was extremely inconsiderate.

Me: Everybody opens doors this way, what'd I do?

Her: There were people behind you taking a test and that was extremely inconsiderate.

Me: Seriously, I didn't slam the door, why would you think that?

And basically she went on calling me inconsiderate for a while. She also mentioned something about me not supposed to go inside the building, to which I responded, "Oh okay, I'll just leave now", to which she continued calling me inconsiderate. We were attracting the attention of people standing outside the outermost door at this point, I think. Then all of a sudden, the woman said to me, "Have a nice summer" in this very fast and brusque tone. She then rushed past me and left. 

Honestly, I'm just so pissed. I can't imagine what I did wrong. I've opened doors in this building for years and not once has anyone berated me for my door-closing technique. I'm pretty sure I didn't slam the door, I didn't hear a slamming sound and besides, I'm pretty sure more people would have noticed if I did. The door I chose to open shouldn't have mattered, there were even more test taking people sitting near the other entrances. 

Thoroughly confused by this time, I left the building, taking special care to close the outer door without a single sound, determined to put it all behind me. 

To top it all off, as soon as I got in the car, my mom started berating me for forgetting to sign up for a summer school course (I didn't fail a course, this is for advanced credit). The sign up deadline is the 30th. I promised her I would sign up today, but she kept insulting me and calling me irresponsible and lazy. It's just a sign up, mom! Stop overreacting! But of course I didn't say that, it's not a good idea to piss my mom off when I have no way of getting home on my own (and yes, I know this is indicative of other problems, but that's off topic for this). Plus, I was still stewing over that woman's behaviour towards me.

I was really looking forward to unwinding after that exam. Right now I'm just tense and pissed off. I know that I will inevitably meet people like that woman everywhere in the world, but this incident just came at a really bad time and I can't stop thinking about it.

Seriously, Glow community, was I in the wrong? What'd I do? This is both a rhetorical question and a question looking for serious answers.