Agreed. Given it's a nascent product with few users/retailers and low barrier to entry (there are at least a dozen similar scan-code-for-punch-card apps), it sounds like a pure talent buy. And $10MM sounds high if that is truly the case.
Secondly, it is interesting because there are indeed a bunch of other punch-card replacement apps. Even here in Australia I know of at least two. If it's a pure talent acquisition (which seems to be a logical conclusion) then it is indeed quite a large sum.
I can't imagine Google wouldn't already have begun development of a similar concept when creating Google Wallet.
It's fantastic for the founders though. Not having met them, and just based on what I've read here, they seem like great guys.