Shifting isn't all about mashing the levers to their mechanical stops, there's a bit of "feel" to it. There are limit screws that sets how far the derailer can go, but if you set them too tight upshifts can become hesitant or even completely locked out. You need a balance between a decently tuned bike, AND the knowledge not to shift too hard.
It shouldn't be a frequent thing, but I think it's a mishap we've all have tried occasionally.
Easing up on the pedals will usually make shifting a lot smoother.
The left/front shifter/derailer move in a bigger step than the right/rear, so there's good reason for it to be less smooth than the right/rear. But whether your still is louder/rougher than expected can't be determined over the net.