Hi Lucy - I'm sure the listing agent will find out more details tomorrow about what is going on at Bank of America. If there is still no answer, the listing agent can escalate the question at BOA. Unfortunately, none of us can tell you more than the listing agent can about your specific situation. It is not the norm, but there are times when it has taken two weeks to get the signed addendum back from a bank.
For REO properties, I have not heard any horror stories about BOA after they accept an offer. I used to list BOA foreclosures myself. I have experienced many horror stories on the short sale side, though, but the two things are handled by completely separate areas at BOA.
My best GUESS is that it is a good sign that it has been removed from the BOA site - implies that BOA considers your offer to be THE offer. And as far as the other websites, the listing agent controls the status in the MLS. So this is also a good sign - apparently the listing agent changed the status so no one else could make an offer on it. So it seems like you have an exclusive on the property at this point. It sounds like it is just a matter of waiting for everyone at BOA to get back from the holiday and sort out what is going on :-)