Toronto-based fashion designer Lucian Matis said he had no idea that Sophie Gregoire Trudeau had chosen one of his dresses until he started to receive photos from friends and fans of the prime minister's wife from Thursday's event at the White House.

"What an honour for a designer to have their dress on the first lady," Matis told CTV News Channel on Thursday. "It's very, very exciting."

Matis said the "bold and beautiful" red and pink dress Gregoire Trudeau opted to wear as she greeted the Obamas on Thursday was actually a "last-minute addition" to the other samples he had provided for her.

He said the dress is part of his spring/summer 2016 collection.

"I really appreciated working with Sophie," he said, adding that he had expected she would opt to wear something custom made, opposed to something that's part of a collection.

"She's very classy, she knows exactly what she wants, and it was an easy process to work on this."

For the highlight of the Trudeaus’ visit to Washington – Thursday night’s state dinner – Gregoire Trudeau wore another Lucian Matis design, an embroidered cap-sleeved purple dress.

Matis said he hopes the recent exposure will mean more international attention for his designs.

"We're hoping to see sales, and also the brand to be put on the map internationally," he said. "I must say, for Canadian designers, it's very hard because there's a lot of competition out there and it's wonderful that we got this."

PM Trudeau arrives at state dinner in Washington