Correct me if I'm wrong...

But - in the README.txt file in the css directory shouldn't:

'tlf2-alpha-default.css
* Loaded for all layouts using the alpha grid (i.e. not the mobile layout).
* Default media query: n/a. Applied to all layouts using the alpha grid.
* By default the alpha grid is applied when the device width is at least
740px wide.'

be

'tlf2-alpha-default.css
* Loaded for all layouts using the alpha grid (i.e. not the mobile layout).
* Default media query: n/a. Applied to all layouts using the alpha grid.
* By default the alpha grid is applied when the device width is greater than
740px wide.'

with 'at least' replaced by 'greater than'.