Is 32x32 hi-res? 'Coz that's what TMO has and the TMO bookmark icon has also changed to the screenshot.
Actually, I wish the browser would not insist on updating the icons every time it starts. Every time I visit a certain supermarket (that provides free WiFi for its customers that is on my network list), the browser pops up asking me to log in, as per this TJC post. And every time it does, all my bookmark icons are erased and replaced with the default stars. Note this happens without me doing anything at all. Most of the times I only notice when I get back home and want to use the phone. Why do bookmark icons have to be updated any other time than when the bookmark is created?