Q:

Is unscheduled, on-boot chkdsk behavior like this normal?

I haven't been able to find a conclusive answer for this question, so I thought I'd ask it myself...
My Win7 PC has been running all but bad the past year or so I've owned it until today. I was trying to install a few dependencies for atom.io, when my PC froze. I rebooted the computer to find an unexpected chkdsk scan. I waited for a bit, and a few messages popped up, such as:
Deleting corrupt attribute record (128, "") from file segment xxxxxx
Deleting index entry xxxxxx in index $I30 of file yyyyyy

A few other things came up as well, but I was not able to capture them. I believe the gist was something about "orphaned files", and something about free space being marked as allocated in the volume bitmap.
I'm genuinely worried currently, as this has never happened before. In the research I've found, I've seen two sides: one being "It's fine, just let it sit", and the other being "Back up your disk while you still can- the end is near". I don't know which one to believe, and wanted a second opinion before doing anything.
Update during writing: My computer seems to be booting normally now- however I am still concerned for the health of my hard drive. Anything you guys could offer would be great. Thank you.
Update 2: I now have access to the Event Viewer, and have created a pastebin with the chkdsk log's contents.

A:

I was trying to install ...

That implies the PC was in the process of writing onto the disk.
ChkDisk coming in on the reboot is expected and normal behaviour, and from what you have typed I cannot tell there being a true problem, other than your half finished installation.
You may have entries in the system logs that will show you at least some detail on what chkdisk actually did.
If you re-run chkdisk and it tells all is OK (no changes), then you should not need to worry.

