ABC News' Michael Falcone reports:

As news organizations reconstruct the timeline of how the Paul Ryan pick went down and who knew what when, note this:

ABC News received an advance clue from a source inside Romney campaign headquarters on Thursday. On the board that lists Romney's whereabouts, the candidate's Friday schedule had mysteriously changed overnight.

Up until Wednesday the board read - "Office Time" - for Romney on Friday, but by mid-morning on Thursday that had changed.

"Office Time" was erased and replaced by the words "Sikh Service."

Next to that notation were three letters, "OTR," which in campaign speak, typically stands for "off the record."

Ryan was the only one of the vice presidential short-listers to attend Friday's memorial service in Wisconsin for the victims of the Sikh Temple shootings. Romney's son, Tagg, also attended the service, according to a tweet:

@tromney: In Milwaukee today along w #RepPaulRyan and #GovWalker to represent my family and offer condolences to the Sikh community

It was sometime after the service that Ryan was smuggled out to Virginia for Saturday morning's announcement.

The board is posted for all to see at Romney headquarters facing the cubicles of aides who work on the Romney advance team - those who likely helped plan and keep secret Saturday's announcement.