I'm seeing this behavior too. My phone is T-Mobile S2 (SGH-T989), not rooted, Android version 2.3.6.
I thought it might be some sort of power saving setting, but I've checked and the power saving settings that can be used to turn off bluetooth are disabled. And Bluetooth will turn off, even when the battery is fully charged. It never happens when in use - I just find when I come to use if that it is turned off, and it like Surfcity, it can take several attempts to turn back on.
The only bluetooth device I connect to is Ford Sync.
Really irritating when it takes several minutes to get bluetooth to connect, especially when I do a lot of short trips!