Growing fast or human error?

[Alexandra V]

I've been weighing my 2010 male every now and then since I got him in June and he seems to be gaining weight very quickly. When I got him I was told that he was eating one hopper per week at the pet store, and I bumped him up to one hopper or one small adult mouse every five days because he's growing and needs the extra food.

We brought him home July 7th, and on July 19th we weighed him and he was about 60g.

Then on August 5th he weighed 100g

Then yesterday, August 27th he weighed about 140g.

Is it just me or is he growing fast? Or maybe my scale isn't accurate?