Does Donald Trump have tapes of his Oval Office conversation with former FBI director James Comey? Press secretary Sean Spicer didn’t deny a Trump tweet that suggested as much, saying Friday that the president “has nothing further to add on that“ but that the tweet wasn’t a threat against Comey, per se. Trump himself has said that the press shouldn’t take anything he puts quotations around so literally. But Trump’s own history of self-surveillance invites the possibility that these “tapes” could very well exist.

The Washington Post compiled a run-down of instances where people have written or spoken about moments where they believed their conversations with Trump were being listened in on. There were the two Post reporters interviewing Trump about Trump Tower, whose order for two waters and a Coke was brought to them without anyone speaking to a person outside the room. Last summer, news broke of Trump eavesdropping on phone calls at his own Mar-a-Lago resort.

Concern about his “tapes” tweet prompted two House Democrats, John Conyers Jr. and Elijah E. Cummings, to request the release of any such recordings of conversations. They wrote that, “Under normal circumstances, we would not consider credible any claims that the White House may have taped conversations of meetings with the president. However, because of the many false statements made by White House officials this week, we are compelled to ask whether any such recordings do in fact exist.”

The Presidential Records Act of 1978—passed in the wake of the Watergate scandal and Richard Nixon’s own notorious tapes—requires presidents to archive any recordings made inside the White House, and to release the tapes to members of Congress if ever subpoenaed.