Is it a red wave , or are California voters coming down with a case of blue flu? These are questions political insiders and data nerds are trying to answer after Republicans showed surprising strength in the first wave of mail ballot returns for next month’s primary election.  GOP voters accounted for 34% of early ballot returns as of Friday, up 8% compared to the same stage of the 2022 midterms, according to data compiled by research firm PDI . Steve Hilton (left to right), Xavier Becerra and Katie Porter are all jostling for position ahead of the June primary election. REUTERS Meanwhile, Democrats made up 41% of early returns, down 7 points from the same moment in the primary election four years ago. Independent ballot returns were up 2% compared to 2022. Assemblymember Carl DeMaio, a San Diego Republican, cautioned against over-interpreting the numbers but said the trend is encouraging for conservatives.…