We're talking Ai CS5.
I have an artboard with a blend between 2 wavy paths, the kind of thing you hope the customer won't ask for again :-)
One path is aligned with a horizontal guide high on the artboard and with another one at the bottom.
I draw a line segment between the two guides, nowhere near the blend, and expect to get just a boring straight line. Instead Ai draws me a stretched version of the blend, starting at the top with the first path and passing all the blend steps arriving at the bottom with the second path.
Sorry I have to describe it like this, but when I tried it again it didn't work anymore, so I can't show you the result. Can anyone explain what happened here?
Looks like you were in the Isolation Mode of the Blend object - you might have accidentally entered this mode without realizing it by double-clicking on the Blend object. Now when you were drawing a simple line, the blend is getting redrawn because now it sees 3 paths to blend between instead of 2 paths.
Hope this helps.
Excellent answer, Sun Rays, thanks a million! It looked awfully weird to me, but now that you explain it it really makes sense.