My completely uneducated guess as to what went down, given the minimal facts/gossip available atm:
1. RE announces his resignation as a pre-emptive strike, preventing DB from firing him.
2. DB decides to take the high road and puts out a statement, one that notably says retirement is Randy's decision and that DB will continue to review.
3. RE & DB's meeting today doesn't go well, to say the least, and DB says "sayonora" (we can always throw in a locker room blow up just for fun).
I could be right. I could be wrong. Not sure what else makes logical (not emotional) sense.
A boy can dream...