Yahoo! Advertising Services (formerly overture.com) email address leak

A long, long time ago there used to be a company called Overture.com that did online advertising, and it was acquired by Yahoo! some time ago.

Now, I use a unique email address for every service I use, and today I was surprised to see the address I used for Overture being used in this spam. I believe this is the first time that I have ever seen spam to this address, so I assume that this is a recent leak of addresses (and Yahoo! has had all sort of problems with breaches at the Heatbleed bug recently).

The botnet sending out this spam does seem to have access to leaked email data that I haven't seen used before. So is this an early warning of yet another problem at Yahoo?