Did you by chance get a picture. I have seen rough sawn be both barely rough and very rough depenging on the mill. I have also seen it with an almost "combed" texture.

Here's a photo. It's so difficult to convey texture in pictures. The grooves along the grain are pretty deep. I'm not against it visually, but I do want to make sure it doesn't indicate a quality problem.

No issues form my point of view. Looks to me to be 1x6 R.S. Shiplap Common (actually probably graded #3 & Better) Cedar. Have it seen it smoother and rougher.

From a homeowner perspective:
We have lived in 2 Cedar houses from the same builder. One we built, and upgraded the cedar. The second house we were the second owners. The cedar was not upgraded, and had knots and splits, and holes where the knots had been. You could read the words on the underneath wrap. We had also kept up with maintenance & staining the first house.
We had to replace the cedar on the second house.
The houses were built about a year apart - same environment.

My recommendation is to look closely at a sampling of the boards -- more than 1 -- and compare the grades before you make a decision. Learn about how the boards are graded and the acceptable splits, knots, etc.