Recently, Elon Musk lashed out at a new analysis claiming that nearly a quarter of the more than 400,000 advance reservations for Tesla's Model 3 battery-sedan have been canceled.

But a closer look at Musk's comment raises a different reason for concern: The prospect that new orders may not keep up with Tesla's long-awaited production ramp-up at it's suburban San Francisco assembly plant.

When it opened the order bank up ahead of the Model 3 production launch in July 2017, Tesla saw a rapid burst of reservations, complete with $1,000 deposits. But with many potential buyers still uncertain about when they might be able to actually take delivery, investment bank Needham & Company on Thursday issued a report claiming 24 percent of those reservations have been canceled – which echoed a June study by data site SecondMeasure, which estimated a 20 percent cancellation rate.

“Dunno where this bs is coming from,” Musk said in a Thursday night tweet. If anything, he boasted, the automaker had received 5,000 new orders for the Model 3 the week before, as well as 2,000 orders for the older Models S and X.

Musk tweet

A spokesman for Tesla told CNBC that, as of June 31, “The remaining net Model 3 reservations count at the end of Q2 still stood at roughly 420,000, even though we have now delivered 28,386 Model 3 vehicles to date.”

For those who are now translating reservations into actual orders, as well as new customers, the spokesman added, delivery will come in “approximately one to three months.” Meanwhile, three people who placed early reservations spoke told CNBC they have heard from Tesla in recent weeks, indicating they could take delivery even sooner than that.

But the numbers don’t necessarily add up. As the second quarter ended, Musk announced that the carmaker had hit its revised goal, producing 5,000 Model 3 sedans during the final week of June. Tesla has now set a goal of reaching 6,000 a week within the next month and, longer-term, is aiming for the original target of around 8,000 weekly. That was the figure Musk had announced previously, before things headed south at the Fremont, California assembly plant.

Even at that highest figure, it should take more than a full year for Tesla to meet existing reservations, assuming everyone does follow through in turning those into orders. And that doesn’t take into account brand new orders, like the 5,000 Musk claimed to have received last week.

In other words, if Tesla can get you a Model 3 in no more than three months, it suggests that either more reservation-holders have backed out than it claims — or that a high percentage have so far declined to transform those reservations into actual orders.