The Australian Idol winner completed his cross-examination on May 24, but after another witness - Christian Bugno - revealed the pair exchanged text messages about disputed evidence before that date, he was brought back to the NSW District Court on Monday.
In 2016 Mr Bugno arranged for the entertainer to perform at his Venice wedding, and says his father paid for the business-class flights of Sebastian and his manager Titus Emanuel Day.
Day - who managed Sebastian via 6 Degrees between 2009 and 2017 - is accused of embezzling Sebastian out of almost $900,000 between 2013 and 2020.
The 49-year-old has pleaded not guilty to 50 charges including fraudulently embezzling money allegedly owed to Sebastian through royalties and performance fees.
He also denies 50 alternative counts of larceny, or stealing.
Day says Sebastian owed him money on commissions, gifts he received, and for flights that he claims he paid for to attend the groom's Venice wedding.
Last week the witness revealed Sebastian texted him on May 23 at 12.27am local time in Las Vegas, where Mr Bugno lives, saying: "Brother sorry but this is so urgent cause I'm in court".
Day's barrister Dominic Toomey SC asked for Sebastian to be recalled to question him about this.
While Sebastian was ordered by Judge Timothy Gartelmann not to discuss his evidence "you are to give," he was given an exemption on May 23 to meet with the Crown about past testimony.
"Did you think you were not in breach of that direction?" Mr Toomey said.
"Everything I did was by the book," Sebastian said
After he was presented with an "incorrect invoice" in court, he knew Mr Bugno would have the records of paying for the flights so he thought it obvious to ask him for them, Sebastian said.
Mr Bugno testified he initially repeatedly contacted a company called Vogue Entertainment to arrange for Sebastian to perform at the wedding.
But when he had no response, he contacted the singer directly.
He said he did not receive any invoice from Vogue but paid the performance fee to Day's company, Six Degrees.
Mr Toomey quizzed Sebastian about the meeting he had with crown prosecutor David Morters SC and his junior counsel.
"I said to the Crown I know I can text him directly. I know Mr Day didn't pay for the flights, so I got the information that I know they would need, not just my word for it," Sebastian said.
Meanwhile, a juror was formally discharged due to personal reasons, leaving 12 remaining members on the panel.
The trial continues.
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