Not really. 250g is almost 9 oz. The US standard is 10 oz at 10 weeks, which is about 284g. That leaves them time to get to full weight of about 12-15 oz at full adult, which is around 12-14 weeks.
Sugar is probably fine. The 1g loss could have been the difference between weighing her just before she pooped one day and just after she pooped the next.