The MAVEN mission has measured an electron temperature spike at altitudes where the Martian atmosphere becomes optically thick and changes occur in the atmospheric chemistry. The temperature spike is consistent from orbit to orbit, but changes in location based on solar zenith angle (SZA) and has only been observed for SZA <80o. This letter presents the conditions under which it is observed and discusses possible sources. The electron temperature spike seems to be co-located with a temperature dip in the neutral atmosphere. The observed temperature spike/dip might be indicative of an inversion layer in the Martian atmosphere. The altitude location of the electron temperature spike is in the lower dynamo region where the electrons start to be unmagnetized. The observations are unlikely to be significant for overall Martian plasma dynamics, but are a clear indication that the large-scale Martian atmosphere is still not completely understood.