I’ve encountered this as well. I’m not sure why it happens, but here’s what I’ve used in my own projects as a workaround:
background-image: -webkit-linear-gradient(top, rgba(255,255,255,0.001) 0%, #fff 5%, #fff 100%);
Instead of giving Chrome a “transparent” value, give it something very, very close to transparent.
Edit: I forgot to post a link to my own version, which renders as expected in Chrome 21 (Windows 7).