Would I be correct in assuming that was a job in shandong province?
Would i also be right to think that you had spent time in sub-Saharan Africa just prior to applying for the z visa? It would not be uncommon of many countries around the world to seek further information about the state of your health in such circumstances.

There are myriad factors that apply across the nation and within provinces regarding what is required to get the z-visa and then residence permit. As has been posted on this board before, a lot of the regulations also seem to be governed by and change as a result of issues in supply and demand for fts. Where a region has high demand for fts it is sometimes the case that regulations are relaxed or sometimes simply ignored. Most cities in Zhejiang for example don't require applicants for the z-visa to have 2years experience and they don't require teachers to come from a 'Big 5' country whereas other provinces seem to be quite strict about this as well as requiring teachers to jump through hoops in regards multiple health checks.

Certainly authorities in China have suggested a tightening of regulations for foreigners working in china but that would likely involve treading on a few local businessmen's toes as it is they who benefit most from hiring foreign teachers (legally or otherwise).