Contreras is an Obama appointee who also sat on the FISA court while the Trump team was under surveillance by the Obama administration. Judge Emmet Sullivan, an Bill Clinton appointee, was randomly assigned to take over the case after Contreras' recusal.
Of note, Contreras was appointed to the FISA court on May 19, 2016 - before the warrant to surveil one-time Trump advisor Carter Page was issued "in the summer" of 2016. It is unknown whether or not Contreras was involved in the decision, or whether he was involved in surveillance on Michael Flynn.
In fact every single FISA Court judge was appointed during the Obama administration:
Michael Flynn pleaded guilty last Friday to a false statement charge brought by Special Counsel Robert Mueller's office in relation to the Trump-Russia investigation. The retired Army lieutenant general and director of the Defense Intelligence Agency was fired 24 days into his role as National Security Advisor for lying about his meeting with Russian Ambassador Sergey Kislyak. Flynn also admitted to lying about his dealings with Turkey as a private lobbyist.