Possible reason for DC visit:

Merit reviews ensure that applications are evaluated through a process that is fair, equitable, objective, and transparent.  Merit Reviews for discretionary[3] grant programs may be carried out through a variety of approaches such as face-to-face meetings, utilizing technology for remote discussions, or through independent assessment of individual reviewers; however, CDC conducts all merit reviews according to the following standards

https://www.cdc.gov/grants/applying/review-process.html