Interesting. If you received the email, but the Boost stats symbol is no longer there, it sounds like there was a curational error that was quickly corrected.

"Meta" stories (ie, stories about making money on Medium) are not eligible for Boost, as per our guidelines here: https://help.medium.com/hc/en-us/articles/360006362473#h_01H7B71M7VN7HJW5QFSPVFNRZK