If there's an offer for DDD, it's probably a "letter of intent" that's already been signed by both parties. The buyer would now be doing their due diligence and they may have found the purchase rights "poison pill" and identified it as something that needs to be removed the offer to go forward and be announced.
Expiring it one month early must be because the purchasers want the deal in this fiscal year (2011) rather than the next.
It could be a merger or an acquisition. If so, we should hear very soon.