Id be curious what self-reported medians had been in previous years so that the comparison is apples to apples. Would make sense that people who are going to go through the trouble of self reporting may be more high-strung or have better scores. Who knows.
Former admissions officer here. The GPA that law schools use for ranking and reporting purposes is the LSAC cumulative GPA. The CAS Report contains a lot of information about your grades but the cumulative GPA is the one that really matters.