Linen weft twisting?

I am weaving towels and using cotton for the warp and linen for the weft. The left selvedge is lovely. On the right selvedge, however, it looks like some twist is built into the warp throw. The selvedge isn't always laying as nicely as on the left side. I have stretches of lovely right hand selvedge, but also long stretches of the twist. I can't find myself to be winding the bobbins or throwing the shuttle differently--but I must be doing something wonky. Thanks for your ideas!