Hi!
No, that is a very average weight. By that age, most piggies are already very close to their eventual adult weight
However, like humans, guinea pigs come in all shapes and sizes. While a large piggy can be underweight, a small piggy can be overweight at at this weight. That is why we encourage our members to not just weigh once weekly as part of the regular health monitoring and body-onceover but to also check the 'heft' around the ribs to work out whether your piggy has a good weight/size ratio and is not too fat or too thin at any stage in its life.
There are also some conditions like ovarian cysts or bloating where a piggy itself is actually losing weight while the scales tell otherwise - but the feel of the 'heft' will tell the truth.
Weight management and understanding what weight changes can mean can be a very valuable and potentially life-saving tool.
Please take the time to read our weight guide, which explains in detail how you judge the heft, how weight changes throughout a piggy's life and what you are looking out for during the weekly weigh-in; when to see a vet and step in with syringe feeding support etc.:
Weight - Monitoring and Management