My plants at home, or at least some of them, are doing this now, too, but none of those pictures turned out particularly well. This plant is the last one remaining of the five or so that I brought in to work, and it's done shockingly well in the heat and humidity of the greenhouse -- I just moved it into a 6-inch pot, whereas some of the plants I grew at the same time (see older post) are still in 3-inch pots at home.
I've also recently been informed by a customer that this is definitely not a rex begonia, it's a fibrous. It's unclear whether 'Coffee Texas Star' is the right or wrong name for it: although I found the picture on a site which was mainly about rexes, and I'm willing to believe that the customer is correct and it's actually a fibrous, I remember the page being ambiguous as to whether every Begonia on the page was necessarily being identified as a rex. So we're still trying to figure this out.
In any case, the flowers are only sort of ho-hum, but it's nice, I guess, that it's happy enough to flower.