Baby Weight Gain

In 6 days my little man has gained 10oz. He was born at 6Ib 8oz and now at 2 weeks (and 2 days) he's weighing 7Ib 4oz! Anyone else found their baby gaining weight fast? My health visitor weighed him twice because she couldn't believe it. He's exclusively breastfed and I was worried about my supply until now, he's already outgrowing his clothes!