I experience the same issue as the op.
It definitely feels like my Magic Mouse 2 is cutting my thumb with its aluminium base because the touch panel is not positioned properly. Moreover, the touch panel on my mouse can actually be moved about 1 ml to the right and expose the sharp aluminium edge under it even more.
The Magic Mouse 1, that I used previously, didn't have this defect. I've tried 3 2nd generation mice in the store and two of them had this issue. I don't know if this problem is widespread and people just don't notice, or that I'm being unlucky here.
I don't have Apple Store in my country, one of the official service shops told me that it's a "cosmetic defect" and declined to look into it. Going to try another service later this week.