Cold feet, saw something they liked better, couldn't get financing, decided they didn't like the color of the bathroom, too close to the mother-in-law, etc. Could mean any number of things, none of which would turn out to be relevant to you or your concerns. Take a look at the property, get a good home inspection, and make up your mind rather than speculate. You could also call the broker and see if they can/will shed any light on this.

Possible, but 48 hours after an offer would be pretty quick for getting an inspection appointment lined up, completed and the report received. You may not know without seeing the house for yourself and pursuing potential issues.

We had a deal on our old house fall thru one day after we accepted because the buyer came to the realization that 3 acres was too much for them to handle. So it goes. We worked with one of the other 4 offers that had come in.

Now there is a chance to offer less than what they are asking. :-)

Everyone thinks when a house comes back on the market there are structural issues. Truth is, most houses have a deal or two fall thru for various reasons. (Especially in the first time home buyer price range). There are a million reasons for it, most of it has nothing to do with the house.