[Denvercoder9]

> What surprised -me- was that all three boosters were brand new, rather than, say, expending a booster that's already flown half a dozen times or such.

Using new boosters was probably a contract requirement, but even if it wasn't, the Falcon Heavy center core isn't interchangeable with regular Falcon 9 cores, as it has to be strengthened to handle the additional load the side boosters put on it.