I kept looking and found Cummings v. Missouri, 71 U.S. 4 Wall. 277 277 (1867)
That defines Ex Post Facto in a SCOTUS decision-
An ex post facto law is one which imposes a punishment for an act which was not punishable at the time it was committed, or imposes additional punishment to that then prescribed, or changes the rules of evidence by which less or different testimony is sufficient to convict than was then required.
Doesn't the combination of laws here constitute ex post facto? He plead guilty to the crime at Point A before two laws that combined have imposed an additional punishment to "that then prescribed" - and as mentioned earlier in the same case point 2 of the syllabus "Deprivation or suspension of any civil rights for past conduct is punishment for such conduct."