See I kinda thought Gaeta was upset that he got a beat down and almost murdered for saving her bitch ass, and no one has ever apologized and here's Kara back from the dead and Bill Adama is seriously expecting him to take her seriously.

And she wasn't exactly being patient either. And Gaeta was needing to explain really basic astronomy terms to her and make sense out of her description.

On an aside, I don't think he lied for nothing - I think he lied to accomplish a task -to stop Baltar.