Has anyone noticed some med schools charging for an extra semester during 2nd and 3rd years?

Did you look at Univ of IL?

https://registrar.uic.edu/tuition/professional/pdf/fall-2017-spring-2018-professional-tuition.pdf

Note the tuition ranges for med school based on number of credit hours. It appears that those lower amounts may be for summers.

Note the mention on med school lines that assessment is over 11 terms. That sounds like 8 regular semesters and 3 summer terms. But I could be totally wrong.