@include layout(4 (240px 60px)); works correctly, and gives 0.25 gutter size.

@include layout(4 (240px 0.25)); causes Sass to carp with error:
Sass::SyntaxError: 0.00104/px isn't a valid CSS value.

Is this expected behavior? I have a patch to fix it, but just want to check first if this is intentional or not.