Maybe not verbatim, but it's certain that some of the space agency's scientists were shrugging and asking something like that once they got a good look at some data from the Chandra X-ray Observatory.
Our favorite still-really-a-planet-no-matter-what-that-doof-Tyson-says emits X-rays. Now, things that emit X-rays in space are generally hot, gaseous or surrounded with a strong magnetic field. Pluto is 0-for-3 on that score, being cold, rocky and decidedly un-magnetic. Which means that NASA almost didn't use Chandra to study it. The possibility of it emitting the rays Chandra is supposed to detect was considered so low as to not be worth the time.
Using Chandra data as well as that from the recent New Horizons probe flyby, project leader Carey Lisse said that scientists think the radiation comes from Pluto's atmosphere interacting with the solar wind -- streams of charged particles given off by the sun. This means its atmosphere is more substantial than believed and that Pluto's not doing too bad of a job holding onto it. Lisse said that other distant objects may show the same X-ray activity, which will be one of those facts that causes astronomers to get positively giddy with uncertainty.
Because pretty much nothing excites a scientist like something he or she didn't expect to happen. It's more or less why they took the job in the first place.