The last three times I've rebooted my SP3 it has asked me for the Bitlocker recovery key.  I don't recall turning Bitlocker on, it may have been enabled by default (and I don't have any particular need for it, as far as I can tell).  I've googled to see if there's an obvious issue, but there isn't anything that leaps out at me.  I've checked for updates, and it's completely up to date.  I haven't done anything "new" or different in the last few days to prompt this, so it's a mystery why it's started doing this.

Understandably, it's a hassle having to enter a 48-digit code each time I restart my SP3.  Can anyone suggest why it may have started doing this, and ideally how I can stop it asking for the key?  I'm hesitant to turn Bitlocker off - even though I don't have a particular use for it, there's obviously something wrong.  I can't imagine that Bitlocker should do this if it is working without fault, so turning it off would just mask the problem rather than solve it.