Another stange gift of the elves or lost contacts?

[Silmarien]

I was reading through a bloopers page and one of them is

Legolas’ eyes are brown (normally blue) when he is arguing with Aragorn before the battle of Helms Deep.

It is corrected by someone saying that elves' eyes turn brown when they are distressed. [img]smilies/eek.gif[/img]
I have never heard this before and was also under the impression that elves could have eyes of any (normal) colour. Is there any one who knows any more about this?