Does anyone own this tank bag? When mine arrived it was missing the rain cover. After endless hassles, a replacement was sent, but from the looks of it, it should be permanently attached to the bag at one end (the replacement cover came with a 3-inch elastic band of material that looks jagged on one end, as if it had been cut off. Presumably this end would have been attached in the rain cover storage compartment). With all I've heard about rain covers flying off while in use, having it permanently attached would make sense. If it doesn't normally come attached, though, then it doesn't pay for me to go through more hassle trying to get an exchange of the whole tank bag. Any insight from other owners appreciated. Thanks.