The question seems quite clear, but here is my situation:
Recently, I have graduated with a MA degree in humanities with the highest academic distinction in my country (Northwest Europe). In fact, as my supervisor told me, the last time that a student in our department reached such a level was a decade ago.
Nevertheless my satisfaction, I feel already that I don't deserve such a distinction because:
I studied for a semester abroad and took 4 courses in a country where A's and A+'s are traditionally "easier" to earn than in my country. I, thus, think that I was in a better position to get this distinction than my classmates who stayed at home.
More importantly, I feel guilty because I once "recycled" a paper from my undergrad years for one of those MA courses abroad, while I only vaguely referred to my previous work. Note that I did certainly not use somebody else's work, but I feel that I could have avoided such an act of self-plagiarism during my MA by referring more clearly and directly. The professor of the MA course did not seem to be bothered with my practice, even when I told him twice that I was planning to recycle an old paper.
Good to know:
1° My supervisor told me already not to bother with the first issue because I received even better grades for my thesis and for some courses at my home university during the second semester.
2° I would like to start a PhD program in the near future, but I feel that someone will call me out for my current issues or, even worse, I can lose the current distinction/get my degree revoked.
3° Regarding the paper, I used some major parts of the undergrad paper, rewrote the introduction (adding a literature review) and conclusion. I was also able to publish the paper in a low-tier journal for graduate students (and corrected my mistake by that time.)
How should I deal with my situation? Should I contact the professors in questions and explain the situation? Is this normal to feel like this (aka impostor syndrome) or are these serious issues?
Any advice is helpful!