Retweet error or something more sinister?

Retweet error
Dave mee from Madlab Manchester tried to retweet a message about geeks talks sexy the other day but couldn’t because his iphone4 wouldn’t let him. No idea why, does anyone else know?

The picture was from the official iPhone twitter app – ironically (as Dave puts it), the only two accounts who have thrown this error up have been myself and Loz Kaye’s. Two people pushing for open platforms and transparency… Both accounts are listed as unretweetable?