I am applying to jobs and I have been using my "volunteer" experience at a university's software development laboratory under the experience section in my resume. I say "volunteer" because it was initially paid, but was later revoked due to university policies that I had to be a matriculated student for that position. I continued to work there for more than a year, and the professor leading the laboratory was happy to have me, paid or otherwise. My experience was half full-time and half part-time, which I basically used to help transition my career and build my skills in this field. I was also included in progress meetings, progress reports, and given access cards, so I felt like part of the team.
Now, I am applying to jobs and I have the experience listed on my resume under "Experience" for the entire time that I was there. I had the professor review my resume and he said it looked good and also offered me a recommendation. I thought the description seemed fine, although I sometimes wonder if I should be more transparent about the fact that I wasn't paid the whole time and it wasn't full-time for the entire year.
I have been networking, and I recently met someone interning at a company where I am interested in applying. I told him that I just finished working as a research assistant, and that I am applying to jobs. He emailed the company with a glowing referral, and also mentioned that I was mentored by the professor, who is rather well-renowned. Unfortunately, I was not mentored by him, as I spent most of my time working with his graduate students and I would meet with him occasionally for advice. Now that the company is interested in interviewing me, should I be concerned about this exaggeration? How can I be open about my position that was half part-time and half full-time? I want to be open with potential employers, but I also don't want to unnecessarily complicate the situation or my candidacy.