Sort of, journeys in the other direction are pushed even further north (or, actually north of the straight line) though which I believe is because of the winds. - i.e. it's a factor, isn't it?
[edit] I think it's fair to assume the winds are relatively stable and more intense further north so eastbound (US > Europe) flights might deviate even further to the north.
The appearance as a northbound curve is the effect of the straight Orthodrome/Great Circle line projected into Mercator.
http://en.wikipedia.org/wiki/Transatlantic_flight#Transatlan...
[edit] I think it's fair to assume the winds are relatively stable and more intense further north so eastbound (US > Europe) flights might deviate even further to the north.
http://en.wikipedia.org/wiki/North_Atlantic_Tracks#Route_Pla...
http://earth.nullschool.net/#current/wind/isobaric/10hPa/ove...