It's a lot to read into one speaker's choice of tense. The public record is that LM and its main partner have been fishing for tech demonstration money for a while, and have found some.
DARPA Awards Aerojet Rocketdyne Contract to Develop Hypersonic Advanced Full Range Engine | Aerojet Rocketdyne
Not to say that there haven't been precursor programs, but that seems to be the story on "SR-72".