From The Washington Post:

Copies of the NIE were sent to the House and Senate intelligence, armed services and foreign affairs committees at the time [late April], through normal electronic information channels available to all members, intelligence and congressional sources said. It arrived at the Senate Select Committee on Intelligence on April 26.

In the House, "there was a bit of a snafu with this particular document," said a spokesman for Rep. Peter Hoekstra (R-Mich.), the intelligence committee chairman. "We had a massive computer failure on our classified side." The first that the committee knew of its existence was late last week, when "it was requested specifically by a member. That was when it was found and scanned into our system."

A bit of a snafu?