We did a rescue a couple months back that involved pulling a person up a full pitch. We used an 8.5 double in the hauling system. The person was probably around 150 lbs. The rope is now a little longer than the other rope, probably about 3-4 feet. Can a dynamic rope really permanently stretch like that? Is it safe to climb on? The sheath is not damaged and we could not feel any flat spots... we actually climbed on it number of times since but every time we do a double rope rappel and the blue one is longer than the green, this question comes to my mind... thoughts?

good suggestion. here's the response from Edelweiss:

Dynamic ropes have much more elasticity than you could imagine; a difference of 3-4 feet is nothing when you know that this rope is able to have 37 % elongation at the first UIAA factor 2 fall with 80kg.

Feel reassured, you can use it with no problem, this rope is still safe to climb with.

Best regards
Hervé