I would leave them. Often a home grower does not have the luxury of planting rows north to south and ends up growing fruit with whatever small amount of land is available. I grow grapes now running the row north to south but I grew grapes years ago at another location and ran the row east-west and they did fine. I think if your present vines are in full sun they will be fine.

It would be interesting to look at Google satellite images and see what orientation professional vineyards are using.

Totally leave them, you are fine. One of the best vineyards in Sonoma has their vines so densely planted that orientation does not even matter.

I think I saw online that in the East one wants to plant them in a North-South row, but in CA, in an East-West orientation. It had to do with shading from sun in the West, and in the East getting more sun (morning and evening) so that the vines could dry out from the humidity. Probably doesn't matter all that much for the home grower. Where do you live?