You can, and should, ignore that warning (note that it's a warning, not an error) from epubcheck when exporting books aimed at ADE-compatible readers.
Having said that, remember that you can turn off the font embedding option in the epub export panel, which will make this go away. Do you really want to embed Verdana? Do you have a licence to do so? Would the device's generic built-in sans-serif face work just as well? (To be honest, Verdana is pretty generic anyway.)