That's a beautiful besseae and you got it at a great price! Regarding the way perfect looking flowers drop off suddenly at the end of their life: Over the years, I've heard of a few instances where family members are accused of knocking the flower off a Phrag plant; sometimes, creating quite an argument. For this reason, whenever I realize that a person buying a Phrag from me is a first time Phrag owner, I warn them of this trait. Now that the flower has dropped, that small bud will swell up quite quickly and open up very soon. My mature besseaes tend to have 9 to 12 flowers, opening one at a time in succession, per stem; not counting the flowers on the side branches. So, you've got a lot of enjoyment yet to come from your plant.