I use Dolphin (not mini), and the same situation occurs with or without Jetpack installed. I do not have any setting selected that clears cookies, clear cache, or clears history. I am reluctant to clear the cache on exit, as some things work better when cached.
When I do log in, after entering username and password, and clicking the remember me box, a vBulletin Message box is returned with the message "Invalid Redirect URL (
http://aawforum.org/vbforum/index.php)
Perhaps the invalid redirect is a result of cached data pointing to a now nonexistent page. The 'What's New' 'Forum' etc. buttons work to take me to those areas once the "Invalid..." message is displayed.
While not an issue with this site, I use Dolphin with Jetpack for most browsing as it does have the ability to run flash with 4.4.2. (requires a work around)