Federal and District law requires seller disclosure to buyers and occupants. Download the DDOE Report.
If you read carefully, the DDOE Report is not definitive. DDOE relied on Relux Homes provided lead results from July 2015 which was prior to the start of construction and on "drive by" external visual inspections. That said, DDOE maintains that the onus is on Relux Homes to comply with lead abatement requirements.
Ask for lead abatement permits, ask to speak to the certified contractor accountable for lead abatement during construction and request before and after pictures of interior walls.
As an FYI, the City allows developers to select independent third parties to certify compliance to code which means compliance is rife with conflicts of interest.