Why you might be waiting longer for your Starbucks fix

Trouble may be brewing at Starbucks (SBUX).

Some customers are noticing longer lines and waits for their lattes, a result of the coffee chain cutting down on worker hours, according to BuzzFeed News. That has led some employees to sign a petition asking for corporate headquarters to listen to their complaints about what they believe are "some of the most extreme labor cuts in Starbucks history."

Several employees told BuzzFeed that their assigned hours have been reduced since May, cutting them down to schedules with fewer hours than they want to work.

While it's unclear what may be causing the shift, Starbucks is dealing with several new pressures, and at least one of those was self-inflicted. Sales growth slowed in the second quarter after the company sparked a customer revolt with its revamped rewards program. It's also preparing to increase wages later this year.

"Customers want their coffee and they want it in a timely fashion," according to the petition at Coworker.org. "As labor continues to be cut, it creates an atmosphere where baristas are worn to the bone without being able to take a breath. Cleanliness suffers, speed of service suffers, partners suffer."

On top of fewer hours, baristas are also seeing lower tips, which the petition says is due to more customers using Starbucks' mobile payment app.

"Tips are in major decline. When you factor that in with actual take home pay, it's a scary place to be," the petition said. "Hours are becoming more elusive as store managers hire 10-20 employees at 20-25 hours a week, sacrificing tenured employees."

Starbucks didn't immediately return a request for comment. The company told BuzzFeed that it hadn't changed its labor strategy. "We are not trying to reduce labor. We want our stores staffed in accordance with what they each need," a representative said.

Workers told the publication that store managers use a computer program to determine how many hours they need, which is calculated partly by how many purchases they believe customers will make in a week as well as by past sales. The program then spits out the hours a manager can assign. Recently, workers said, the program was returning fewer hours.

Complaints from baristas are also showing up in social media as some express their concerns on a Facebook page for employees. On a post about Starbucks' new dress code, some workers said they were more concerned with wages and hours. New company guidelines allow baristas to dye their hair and wear fedoras, beanies and other hats, among other changes.

Wrote one worker: "My store gets crazy busy with it being tourist season and being by the beach and Starbucks is making it to where there is 3 people on what usually is a 6 person floor. We're exhausted and need more people. I can live without the purple hair."