Discovery: Yahoo Mail Acting Weird

Whilst looking for banking e-mails I didn't seem to be getting, I discovered that Yahoo mysteriously decided to stop forwarding mail to my gmail account.

Thus, if you e-mailed me at j_m_mcdermott (.a.) yahoo.com in the last month, I only just now got it, and I don't really have time to deal with it, right now.

Doesn't seem to be a reason for it, and I'm still downloading the hundreds of mail and spam mail that will need to cross over.