I think I have found a web rendering bug for Google Fonts in Mobile (iOS 8) Safari. It seems to me that Mobile Safari adds a tiny bit of letter-spacing to all text that uses
Note that Google Web Fonts only exports the regular weight (400) by default, which can lead to Mobile Safari (and other browsers) being forced to impose faux bold.
To explicitly export bolder weights, select "CUSTOMISE" in the Google Web Font font selection pane, manually check each additional weight you require, and use the updated embed code.
)]1