He tweeted before and after the meeting but thought it might be impolite to post messages while the president was talking. While he said he likes his messages to "be as real time as possible," he also said he tries to refrain from tweeting on the floor and during committee.
While there was no indication from the White House or Democratic leadership that the closed door tweeting was problematic, Democratic staffers told ABCNews.com that as tools like Twitter evolve, it's possible that congressional rules could also evolve.
"This is all a brave new world. They have to figure out the rules," Boston University's Whalen told ABCNews.com.
While there's always been leaking, instantaneous leaking, that could potentially reach thousands of people at one go, could present a host of new problems.
For example, when national security matters are under discussion, privacy is an utmost concern. And, Whalen wondered, given all the deal-making on Capitol Hill, will the possibility of a tweeted conversation make people less inclined to come to the table?
"Frankly, what is confidentiality? There's going to have to be a redefinition of it," Whalen said.
But, ultimately, John Wonderlich, policy director for the Sunlight Foundation, told ABCNews.com that the new openness is a sign of significant reform.
"Both sides are trying to claim transparency," Wonderlich said. "We're delighted by that tension.
"It's another interesting example of where technology takes lines that are well-established and makes us re-examine how those boundaries apply in new contexts," he said.