29g is heavier than Darla
He's usually 24-25g, although at last weigh-in he had actually gained three grams! But yes, for a pet shop Robo that's fairly normal I think.
ETA: And I'd actually do the same as kyrilliondaemon suggested, since I've started feeding the hams more fresh foods they've both been eating less hamster mix, so sometimes I don't feed them one day if they have lots in their bowls.