That is very tough to say, but if you don't hear from them in 3-4 days, it's highly likely that they changed their minds. I have seen people get very excited about a house, and then disappear. It happens more and more in this market.
It could be that they are working out some financing issues, etc...who knows..now, your Realtor should be following up with each prospect, and finding out exactly where they stand. So I would ask your Realtor to contact the other Realtor and find out what's happening, or what's not.