In the first two preseason games, the Packers' offense sputtered at times, most notably at the beginning of the game against the Cardinals in Week 2, where the Packers weren't able to put any points on the board until the second quarter, during their third drive of the game.
Slow starts have been a problem for the Packers during games, most notably last year against San Francisco and Minnesota, where they failed to put up any points in the first quarter. In both of those games, a big play would spark the Packers offense, and eventually, they would build momentum and go on to put up more than 30 points.
Although slow starts frequently haven't been a major roadblock to the Packers' success, they shouldn't have to need to go into a no-huddle in order to spark their offense and gain a rhythm, which is what they've had to do in the past two games.
Of course, it is preseason, and it is to be expected for the Packers' offense to be a little shaky, and they will have time to gain chemistry throughout the rest of the preseason.