Weight and age question?

[neverenderday]

This might be one of the more unusual, and probably unwarranted questions, because this about weight GAIN and not weight LOSS and I probably have no reason to worry. My scale broke sometime back in January, and I've kept forgetting to get a new one, but I brought both chin's into the vet in April for a standard check up - however, the vet tech forgot to write down the weight of the one I'm asking about (because I called this morning and they only had the weight of one on record for April). Case is a little over 7 years old, and I've noticed he's been gaining some weight (just by looking at him) over the last three month's. I finally borrowed a gram scale yesterday from a friend and he's a little over 900 grams. Which is, I believe, a good weight - for his make and model, anyway. But he's usually always weighed between 775-825 from what I remember. They've always been on a real lean, standard diet - Mazuri pellets, hay, and every two weeks, a raisin each, and every other day, half a teaspoon of oats. There are no health issues, both seem entirely healthy, but I've noticed the last few months (about 3), Case has become a little more lazy. Not lethargic - the boy will get up and go when he wants too, especially if it's bath time. But he doesn't seem quite so interested in play time as much. He prefers to just chill out on what I've deemed his "Old man shelf" and will saunter out when he wants but that's just to do a bit of checking before going back in.

Like I said, he seems perfectly normal, just becoming more "lazy." Everything gets less active with age, so I'm just seeing if this is perfectly normal for a 7 year old. I just worry about him gaining more weight due to lack of getting his fluffy butt out of the cage for a run. But I guess fat and happy is the way to live. Any thoughts?