Yes, its true. That's pretty much with everything Disney. We had to return balloons twice, both DL I think. One time, there was a freak accident and the balloon hit a tree and developed a leak. Returned it that day. Another time, it started deflating and same thing. I wouldn't keep on bringing it back on multiple trips, just the same trip (1-2 weeks). We always try to get the balloons on the first day because of how long they last. Then, we deflate them, and blow them up at home on occasion. The kids enjoy playing with them. We never bring them back down there though. The balloons also change so that would be odd.
The dory balloons don't deflate like the other ones do. (those are heat sealed)