Grid's custom keys not shown as column headers when downloading grid to file

I have tried this with 7.x-4.0-alpha6 and dev

In a grid where both the row (questions) and column (answers) titles have customised option keys the downloaded table has the values as column headers (questions) instead of the keys.

This makes it difficult to work with long questions!

The column contents (answers) work as expected and I did remember to select "keys" on the download form.

Excellent module though - I hope you can fix this!