The Concord had 12-15uSv/hr [1] (2-3x a long haul flight). The lower bound and best case, workers are fine. Upper bound and European (which are stricter than American, but we're talking international flights) standards are 1mSv (whole body) or 50mSv (effective to skin) [2]. So we're between 4166hrs/yr and 66.6hrs/yr working that would be allowed.
Because it is international they'd probably go with the lowest common denominator, at 1mSv/yr dosage allowed (50mSv/yr for American radiation workers, 150 for Astronauts). And we're just talking flight, not adding the nominal background radiation, which is going to reduce the number of hours even more.
So in short, no, the extra radiation exposure at those altitudes is not minor. It has to be considered if you are going to hire people to fly your plane and attend to your passengers. Airlines already consider radiation exposure. No one wants to do massive medical payouts 30 years from now.
[1] http://aviationknowledge.wikidot.com/aviation:in-flight-heal...
[2] http://www.radioactivity.eu.com/site/pages/Doses_Limits.htm
Addendum: 1Sv in a year is a 5.5% increase of cancer over your entire lifetime. 1Sv in an hour will probably kill you.