So I recently passed my PhD viva with minor corrections. After making these corrections, receiving approval of my corrections, and waiting for permission to upload to my uni's research archive I noticed some mistakes that my examiners nor my PI spotted. Some were minor, which included formatting and grammar errors. Others included the wrong concentration listed for a chemical and forgetting to put quotes and a citation around 2 sentences that I knew was taken from a paper. I made these corrections immediately, but then I began contemplating whether what I did was right.

On one hand, I know my thesis will be a resource for the lab and I don't want it to be wrong or ambiguous for future members. And if I know its wrong and do nothing about it, esp. with forgetting the quotes (=plagiarism), isn't that plain ignorant to not address it? But on the other hand, I feel its quite sketchy because I'm correcting after the fact my examiners approved. My university's policy states that no corrections whatsoever can be made after our division board grants me permission to graduate and submit to the library by notice. I made these corrections before the written notice was provided and stopped as soon as I got it.

What should I do at this point?

Every thesis, due to the length, has at least one typographical error.

The majority of people simply don't notice it, until they dust it off 5 years later to show a student :)

At most places, even when a thesis is passed without correction, there's an opportunity for a final proof. I would think the 'spirit' of the University regulation is that you don't, say, completely change the conclusion or the scientific claims after examination. It won't be there to stop you correcting an obvious typo. There's not a panel of academics in the world would suddenly throw out your thesis for fixing a typo.

Thus, I'd think you're incredibly safe correcting anything that's a typo, prior to final publication. I include adding quotes to that - modern academia fixates too much on copy-pasting, and often ignores what plagiarism is (theft of thoughts and ideas) in favour of lazy Turnitin measures. Not to say copy-pasting without quotes isn't wrong, but it my view one set of forgotten quotes in 500 pages of original thought is far less severe than 500 pages of stolen thought with original text. If correcting the concentration of the chemical changes the actual findings, then that's a much harder (and ethical) question; but I'd suspect it's basically replication of a textbook or the type of decimal-point-in-wrong-place kind of error that's obvious and doesn't carry through to the results.

It will not really matter. The average thesis is read cover-to-cover by 5 people including the author, supervisor, and examiners (I've always assumed the 5th is a proud parent). Many would drop it and be done with it, and not worry about it at this stage, it's to your credit you've done yet another fine proof - but you do also need to accept, no matter how many times you proof it, there will be the odd mistake. The aim in a PhD is flawlessness, the reality is never that.