Honda is not happy that they will be unable to develop during 2015.
Honda is "annoyed" it has been left out of the relaxation of the F1 engine freeze for 2015.
After Ferrari and Renault championed a loophole in the regulations, the governing FIA's Charlie Whiting clarified that while existing manufacturers can now modify their turbo V6s during the 2015 season, Honda cannot.
That is because the rules explicitly mark out a February 28 homologation deadline for new engine makers.
And "As the existing manufacturers were obliged to homologate their power units by 28 February 2014, it would seem fair and equitable to ask a new manufacturer to homologate their power unit before February 28 2015," Whiting said.
We reported last weekend that, at the most recent Strategy Group meeting, McLaren boss Ron Dennis expressed his "concern" that the clarification discriminates against the British team's new works engine supplier.
And a senior source at Honda has now admitted the Japanese marque is "annoyed".
The BBC added that McLaren-Honda has been in contact with the FIA about the matter, and will meet with the governing body next week.
What are the pundits saying?
So far, the press' reaction to the 'unfreeze' situation has been mixed.
Reporting for Brazil's Globo, correspondent Livio Oricchio said he expects Fernando Alonso and Jenson Button to "probably have to watch their opponents fight for the top places" this year.
"Honda have to fight against competitors who not only have a year of experience with their power units, but now have the possibility to make them even better as the season progresses," he added.
But as report in Italy's Autosprint noted: "It is also true that Honda had a year of extra time to design its engine, taking advantage of the experience of what its opponents had to go through in 2014.
"This will have impacted certain technical choices (made by Honda) such as the position of the turbine and the compressor."
Writing in the Spanish daily AS, Raul Romojaro said: "It remains to be seen whether McLaren-Honda will lodge some sort of appeal or seek consultation on Whiting's interpretation.
"In any case, their first objective must be to take advantage of their current absolute freedom of development until March," he added.