Not necessarily Just Enough. It very much depends on the flight Profile of the rocket. It's normal during launch, to turn off the engines once your airborne and cruise until you're at a higher altitude and then turn the engines back on. The reason to do this is to get the additional velocity you Need only after you've escaped the thicker parts of the atmosphere (this is in fact necessary as if the air density is too high you will burn up if you're going too fast).
So if the rocket was already at the right height, it might have only needed the boost to get it to the right velocity. If it fired before that boost, your velocity is lower than planned but your height/atmospheric density could be right.
This is of course speculation on my part. I'm at work and cant access Videos so cant check out what's shown in the article.