Hello,
Thank you for your medical query at DoctorSpring.com
I understand your concern.
It definitely does seem like it has been triggered by the long flight, as immobilisation in the flight does cause the muscles to be sore.
It will gradually get better, but I will advise you to use Advil or Myospas tablet for quicker relief.
You can get back to me if the pain worsens, however it should be fine in 24 hours.
Hope this was helpful,
Feel free to discuss further.