That would explain it. Go pick up a 440, side-by-side with the 390. The weight and overall dimensions will be about the same, but the feel will be different. Neither is going to feel like an old metal-top, metal-handle saw, of course, but there is still a noticeable difference.
The homeowner line of saws, including the 290/310/390 family, utilize the same sort of plastic engine cradle setup that is also used in the MS250 on down. It is a fine design for the saw's intended market and it helps keep costs down, but they just don't feel especially durable, do they? I've owned and run saws in the 290-series and they are durable and reliable saws, if somewhat underwhelming on the performance side of the equation, but they feel strange in your hands if you're used to a saw with more metal in it.
Congrats on your purchase of an 041. Those were and remain good, solid saws. You'll be hard-pressed to find a modern saw in that displacement class that can approach the torque that those old flat engines produce. And if you're used to cutting with torquey saws then you definitely made the right choice. I look forward to seeing some pics of that 041 at work!