Hi,
Thanks for the post -- this is not a new issue in TF, unfortunately. The tiles are in a different projection than in most online map viewers (e.g. OSM and google maps). It's an artifact of TF pre-dating all of the TMS and google map technology.
It's on the list to switch to a Mercator based projection (the same as google maps) but it's a significant development project, so I don't have plans to get to it any time soon.
I find the maps usable as long as you're not looking at extreme latitudes. In AK the effect is pronounced. In the lower 48 not so much.
Cheers