I know nothing about the houses you are talking about, but it could be as simple as they got what they were looking for and signed the contract. We just listed our house for sale (not a short sale) last week, and we had three offers within 4 hours of its being available for showing. We took the full price offer that night, but received an above full price offer the next day. I wish we had waited a day, but our hands were tied and since we got more than what I thought the house was worth I can’t complain.

By the way, the house we bought was a short sale, and I would not recommend going through that process to anyone!