How does this fit into "Mouseprint?"

It was clearly an unintentional error.

I ditto the above; the company made an error, admitted it and made it right.

This is certainly 1 in 10,000 against the companies who intentionally under-fill their opaque packages with as much as (I have seen) 75+% empty space.

You should give the company an accolade.

Edgar replies: David, as you know, Mouse Print* has a long history of covering packaging issues where the consumer is surprised and gets less than expected. This includes slack fill (like movie candy boxes), downsizing (a bazillion examples), and not getting the contents promised (like Starbucks lattes).