"I don't have your name on the list," an Important-Looking Person told a mother and daughter waiting in line. "I can only let in RSVPs."
Their faces fell. The duo began making furious phone calls to correct the problem and get seats.
Up and down the line, total strangers - all in Muggle wear, conventional wisdom being that it wasn't cool to dress in Gryffindor colors at what was ostensibly a press screening - swapped stories about how they killed at Potter trivia games, and wondered aloud at how Harry's first kiss would be handled on screen.
"The books are getting so good," Eileen Foley, 19, of Yardley, said, looking around the person in front of her to get a fix on whether the line was moving. "They're getting so much better."
Like many Potter purists, Foley has one pet peeve about the movies.
"It annoys me when things are different between the book and the movie," she said.
Foley's friend Ashley Dix, 19, admitted that she's "only read the first book."
But she wouldn't dare miss a film, she said.
"There hasn't been a movie that wasn't great," said Dix. "This is really exciting."
When the theater finally opened, Tricia Pompilio, 31, of Philadelphia, was buzzing, too nervous to even stand in line for popcorn. Her worry over not getting good seats assuaged - waiting in line outside, she had directed her friends on which way to run in order to score optimum viewing real estate - she watched the theater grow steadily more crowded.
"I have butterflies," she said.
Pompilio had spent the day before simultaneously re-reading Potter books and re-watching Potter movies. She had scoured the Web for tidbits on the new movie, and animatedly discussed such minutiae as camera angles and and running time.
"This is only going to be two hours and 18 minutes," said Pompilio. "That's too short. That's the shortest movie of all."
As the previews rolled - trailers for I Am Legend, a Will Smith thriller, and Fred Claus, a Vince Vaughn vehicle, Pompilio shifted in her seat.
"I'm shaking," she said.
And then - finally! - the opening scene, Harry striding through a dusty field, confronting his sullen bully of a cousin on a playground and then battling dementors, and Pompilio relaxed.
When the lights went up, Pompilio gave the movie a good - not great - review.
"I think the photography was amazing," she said. "The sets were realistic, the movie was very dark and eerie."
Still, there were misses - the death of a beloved member of Harry's inner circle, didn't seem dramatic or important enough, and there were some key details missing, she said.
Blinking in the sunlight outside the theater, Potter fanatic Wendy Luong, 19, agreed with Pompilio's assessment.
Luong said the major character's death wasn't handled well. "Reading about it in the book made me cry."
Her friend Kris Barton, 20, nodded.
"The movie was a CliffsNotes version of the book," he said. "There were some cool parts, though."
Darlene Weinmann, 40, of Glen Mills, said the movie rated a second viewing. Maybe even more.
"I will probably own it, and see it 100 times," said Weinmann.
Her son Aidan, 13, agreed.
"I liked the action parts," he said. "It was cool."
Aidan's brother Sebastian, 11, gave Order of the Phoenix nothing but praise.
"I liked the effects, and I was surprised and excited because they made a few things happen I didn't expect to happen from the book," Sebastian said.
Check one Potter event off the list. Now, the Weinmanns said, the countdown begins for the next biggest day of the summer - July 21, when Harry Potter and the Deathly Hallows appears in stores.
Contact reporter Kristen Graham at 215-854-5146 or firstname.lastname@example.org.