Yeah, I've seen this alot. You may be right about white-knuckled driving, or maybe just someones habit to grasp the wheel tightly or trying to twist their grip the wheel, some odd habit like that.
I've mostly noticed it on this vintage range it seems like too; early to mid eighties 126, and also early 201's and 124's.
No idea how to fix it; no one ever asked for it to be fixed. Glue idea may work, or maybe a small application of expanding foam (Great Stuff or the like)? Whatever you use MAY make it worse somehow, you're kinda on your own, unless someone here has actually fixed it. My message is mainly to verify that you have a problem that's been seen before.