The Index of the Giant's Comments V―On a Saner Forum, We Wouldn't Need this Index

[Gwynfrid]

I'm not sure an unmentioned detail rises to the level of being, or appearing to be, a "storytelling mistake".

I think Joerg's suggestion makes sense. The question the quote replies to hints at suspicion of a plot hole. And the Giant's response clearly indicates he felt that way, too.