It is actually quite deliberate. NASA and JPL are big on always communicating their work as a team effort, rather than highlighting individual contributors. As a practical example, notice how, during critical events (anytime you have a live-stream from Mission Control), everyone in the room wears the same shirt. Another fun anecdote on the "one NASA" philosophy (albeit at a different scale) is that the Pathfinder lander (if memory serves me right) had a JPL sticker visible from the cameras at landing. NASA was not impressed: although designed, built and managed by JPL, this was a NASA mission. So Curiosity (also designed, built and managed by JPL) only has NASA stickers - but the wheels have a pattern that spells out "JPL" in Morse code and is visible in the rover tracks.