The chief financial officer of Chipotle Mexican Grill (CMG) has completely dismissed any suggestion that his company is suffering as Taco Bell's business has surged.

Is he right? Let's look at the facts.

Taco Bell, owned by Yum Brands (YUM), saw same-store sales soar 13% in the quarter ended June 16. Taco Bell's impressive showing was fueled largely by its Doritos Locos Tacos, which launched in March and became the most successful launch in company history. Taco Bell sold 100 million of these tacos in 10 weeks.

Qdoba Mexican Grill has also seen an uptick in sales, though not nearly to the extent that Taco Bell has. Qdoba, owned by Jack in the Box (JACK), said its same-store sales rose 3% in the second quarter.

Compare that with Chipotle, whose stock crashed last month after second-quarter revenue growth came in below analyst expectations. Same-store sales only rose 8% in the quarter ended June 30, which, although still meaningful, wasn't the 10% gain analysts expected.

So can we connect the dots? Can Taco Bell's gain be impacting the slowdown at Chipotle? CFO Jack Hartung dismisses the idea completely.

"The experience we provide is very different from Taco Bell's," Hartung told Jim Cramer Thursday on CNBC's "Mad Money" program. "We don't think our customers are on their way to eat lunch or dinner, and are thinking, 'Gee, should I have Taco Bell or should I have Chipotle?'"

Hartung added that he didn't see any sort of customer tradedown in the Mexican-themed fast-food business. Customers aren't choosing Taco Bell's lower prices over Chipotle.

"Our customers, they don't talk about deciding to go get a burrito and where should they get that from," Hartung said. "They talk about having a meal that they want to enjoy and they think about Chipotle. So they don't think burrito first, and then Chipotle."

So is he right? I don't buy it. I think many customers definitely think about what kind of food they want and then where to get it. Taco Bell is having a great year, ramping up advertising for its new offerings and reinventing itself after a prolonged downturn when a lawsuit last year questioned the quality of its beef.

The second quarter results don't include the new "Cantina Bell" menu from Taco Bell, which launched in July. The Cantina Bell effort is a clear attempt by Taco Bell to attract Chipotle customers, although neither company wants to admit that.

Is it working? So far, the reviews for Cantina Bell items have been fairly positive. "For practically half the price, the Cantina Bell menu is a definite value, but you do get what you pay for, and the overall quality and taste of Chipotle still has a slight edge over Taco Bell," writes reviewers from Zagat.

The third-quarter results from both companies should prove very interesting, and shed more light on this. Yum Brands' quarter will include the new sales from the Cantina Bell menu, and will offer a better look at the contributions from the Doritos Tacos line after the initial hype around the launch has disappeared.

It may be too early to definitively say that Taco Bell is eating some of Chipotle's business, but the signs are there.

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