Come, daddy, Harry doesn't want to talk to us right now. He's just too polite to say it. ~Luna Lovegood

Hello, Harry!” she said.
“Er — my name’s Barny,” said Harry, flummoxed.
“Oh, have you changed that too?” she asked brightly.
“How did you know — ?”
“Oh, just your expression,” she said.
Like her father, Luna was wearing bright yellow robes, which she had accessorized with a large sunflower in her hair. Once you got over the brightness of it all, the general effect was quite pleasant. At least there were no radishes dangling from her ears.

My mum always said things we lose have a way of coming back to us in the end. If not always in the ways we expect".
-Luna lovegood( Harry potter and the order of the phenoix)

I suspect Nargles are behind it.

I've never stunned anyone except in our D.A. lessons," said Luna, sounding mildly interested. "That was noisier than I thought it would be.

And anyway, it’s not as though I’ll never see Mum again, is it?