Tonight I was cruising on a quiet, flat 45-mph road with the ICE. I noticed that shortly after I began gently accelerating, the engine would suddenly get much louder, as if it's emitting a grunt or groan, but just for a second or two. I think this has been happening for a long while (maybe even not long after I got the car), but I really noticed it tonight. If I continue to accelerate, or stop accelerating, or whatever, the noise goes away, but it seems to happen only at a certain point early in the acceleration cycle.
Does this sound like normal ICE/eCVT behavior, or should I take it in to get checked? Has anyone else experienced this?