It would NOT have been converted before the sale. Dealerships very rarely take vehicles off the front line to do a recall unless it is a severe safety issue. It usually has to be done after the fact by the customer. In this case, the recall doesn't start until late September, so most likely parts for the recall won't be available to the dealerships in a very large quantity until the recall date.
If it was manufactured after the recall was issued (even though it won't begin until semptember), than Nissan would have rectified the issue in their manufacturing process. Check your build date and call 1800nissan1 and ask if you are affected. They will take your Vin# and tell you right away if your seatbelts will need the "energy bolstering.."
I read this thread hoping for a recall for the overtightening / strangulation issue. I guess not.
When I come to a stop and lean forward to look around a corner, I CAN'T MOVE!!! The seatbelt locks at odd times and every time the brake pedal is evenly lightly depressed. I hope they recall this too.