After opening her Hammerstein Ballroom set with "ME!" -- during which an eyewitness tells ET that Swift looked "excited to be on stage and in the company of her fans -- Swift performed such hits as "Welcome to New York," "Blank Space," "I Knew You Were Trouble" and "Love Story."
The celebrated singer opted to close the show with one of her biggest hits, "Shake It Off," which includes the lyrics, "Just think while you've been getting down and out about the liars and the dirty, dirty cheats in the world, you could have been getting down to this sick beat."
Fans on Twitter noticed that Swift seemed to put some particularly strong emphasis on the words "liars and dirty, dirty cheats of the world," and some jumped to the conclusion that this was her way of subtly taking a swipe at Scooter Braun and her old record label, Big Machine.
While Swift -- who, the eyewitness says, made a point to high five fans in the front row and acknowledge those up in the rafters -- didn't overtly mention anyone she may or may not be feuding with by name, some fans felt it was a clear shot after Swift's public feud with Braun and Big Machine exec Scott Borchetta, which went public last week after she put up a lengthy Tumblr post accusing Braun of bullying her by purchasing her music catalog through the acquisition of her former record label.
"Sex is cool and all but have you ever watched Taylor Swift shade Scooter and Scott during a female-led concert after reminding everyone she writes all her own songs #PrimeDayConcert," one Twitter user wrote.
The Prime Day concert -- which, according to the eyewitness, featured a VIP section full of elevated comfort foods including a slider station and gourmet grilled cheeses -- also marked the first time Swift has performed her latest single, "You Need to Calm Down," live in front of an audience, and fans couldn't contain their excitement over the 29-year-old singer's stunning stage design and fun visual elements.
As the audience -- who, the eyewitness says, had the chance to take pics in multiple photo booth installations throughout the night -- departed the high-energy concert around midnight with a limited edition poster, the eyewitness tells ET that some lucky fans also got to leave with Taylor Swift T-shirts, which were launched into the audience. Those who didn't walk away with a new shirt instead opted to collect some of the leftover confetti as a souvenir.
For more on the ongoing drama between Swift, Braun and Big Machine, check out the video below.