Look a little deeper into the reasons as to why. Strange things happen sometimes. But in general even in the good markets its hard to get a home owner to agree to set the asking price where it should be, and in the bad market its worse because they still want the 2008 high prices. Then on the other side of the coin you need a potential buyer to validate it by paying the asking price. Then you have multiple offers on the property that just came on and they turned down a higher one. Is their something unique about the property that really makes it that much more desireable? If I searched in that price range would I find a large number of homes to choose? There has to be something to make you jump $30k and not even question it.
I would proceed with caution. These days for a lot of agent/brokers multiple offers are not too common.
Did you work directly with the listing agent? How long was the property on the market before you made your offer? Did you get any kind of validation that the other party was actually going to make an offer or were they just going to look at the property? You say the prices in the area are now $20K below what you offered - how has it changed that drastically since your accepted offer? Usually market drops take more than a couple days. Did anyone give you the market statistics for the neighborhood prior to making your offer?
The answers to these questions may help us better understand the situation :)
Congratulations on your new home, I hope you enjoy many years there :)