This coincides with a monthslong test at McDonald's of extending breakfast hours all day, part of the broader effort to turn around its U.S. business. There is strong evidence, too, that a nationwide launch could be on the way as soon as October, meaning its need for eggs could be about to increase.
"It's probably not going to be the best timing for McDonald's, unfortunately, but it's part of a longer-term strategy to focus on what's working and increase that," said Nick Setyan, equity analyst at Wedbush Securities, in a phone interview.
Meanwhile, Will Slabaugh, managing director of Stephens, said, "It would definitely pressure their cost of goods sold if they were to roll it out now. It would hurt them near term."
Read MoreMcDonald's all-day breakfast may debut nationwide by October
Fellow fast food brand Taco Bell is also more exposed to egg swings after it rolled out breakfast last year, though a company representative said it has not been hit by the price hike so far.
McDonald's did not respond to CNBC's request for comment.
While restaurants often lock in prices under contract, they do feel the pinch from higher commodity prices if they stay elevated for a prolonged period of time.
"Most are only going to contract three to six months because it's a volatile commodity, and you never want to get yourself locked into all of it," Slabaugh said.
As of Monday, Midwest wholesale prices have risen 135 percent to $2.80 per dozen, from $1.19 per dozen on April 22, according to prices from market research firm Urner Barry. Retail prices typically run even higher.
The problem could get worse if wild birds spread the flu this coming fall when they migrate south.
Read More $6 eggs could be on the way
Restaurants' exposure to avian flu impact is very case specific and depends on whether or not their suppliers have been directly impacted or not by the virus or not.
"Some major corporate chains have not seen an impact to their supply or price. Others have seen higher costs through regular suppliers. Others are completely exposed to the open market and are struggling to source full need," said Brian Moscogiuri, market reporter for eggs and egg prices at Urner Barry, in an email.