One Grey's Anatomy viewer noticed Callie (Sara Ramirez) and Arizona Robbin's (Jessica Capshaw) baby has what seems to be an irregularity in her name: Sofia's full name is Sofia Robbin Sloan Torres, but Arizona's last name is Robbins, with an "s."

What's the deal?

Showrunner Shonda Rhimes explained Sofia's name recently on Twitter, saying, "Her middle name is Robbin Sloan and her last name is Torres. Robbin felt more like a middle name than Robbins."

Does this reasoning make sense to you, or do you think Arizona's full last name should have been included?

For more Grey’s spoilers, click here.

Catch the next new episode of Grey’s Anatomy on Thursday, January 24, 2013, at 9 p.m. ET/PT on ABC.

Source: @Shondarhimes

Rebecca Martin is an editor at Wetpaint Entertainment. Follow her on Twitter @BeccaDMartin.