The Nationals recalled Millas from Triple-A Rochester on Monday, Andrew Golden of The Washington Post reports.
Millas was previously called up April 10 and started that game against the Giants at catcher, going 1-for-3, before heading right back to Triple-A. This latest move corresponds with Washington placing fellow catcher Keibert Ruiz (illness) on the 10-day IL, retroactive to April 12, so Millas should stick with the big-league club for a week or so.