Read a few posts and figured it out!
If they want to cut it three inches longer than the three yards I ordered, by all means - - rip away, but consider this!
If you rip it from selvedge to selvedge, you will definitely skew the fabric ... it may be straight somewhere along the line, but selvedge to selvedge is not the most stable part to rip.
If you are going to rip your borders, then you have a really good chance of having little waste, little distortion, since the lengthwise of a bolt is more stable than the selvedge to selvedge.
I am not professional enough to tell the warp from the weft, but one of them is touchy, and the other one is stable.
Which explains why (when I tried ripping my backing straight while it was on the quilt frame, and I was NOT using the length) ... my backing was skewed, and I did some fancy piecing to make it all blend.