2017 iMac Made Weird Noise Out of Nowhere

I bought my iMac July 31, 2018, so I have not even had it a full 4 months yet. I feel like I started noticing weird hiccups after I updated to OS Mojave version 10.14.1 including the system running extremely slow, or the infamous spinning pinwheel of death a now regular occurrence, but nothing as weird as what I just had happen. While I was working on a homework assignment (nothing out of the ordinary or in any new program or app), out of nowhere my iMac started making this bizarre sound, I don't even know how to describe it because it's been nothing like what I've heard in any videos I found on YouTube or in any other post. While this was happening I tried closing any open programs by right-clicking icons in the dock and when I would right click I would get an error sound and the right-click menu would open then immediately close. I did a restart and it went away but don't feel like this was at all normal and I'm worried there might be something wrong with my iMac. Of course, I couldn't upload a video to this post because nothing with Apple is ever convenient so I uploaded it to YouTube. Here is the link to the video.. https://www.youtube.com/watch?v=-96yOjAqBbI

The closest Apple store to me is an hour away and calling Apple Support is useless, they know about as much as I do! So if anyone has any idea what the deal is I would really appreciate it.

iMac Specifics

iMac (21.5-inch, 2017)

2.3 GHz Intel Core i5 Processor