Could be either - I might try setting the HID and seeing if I can repeat it - but I did a full factory reset and its all back fine working and I dont get the Windows asking me for a pair. Thanks for the help there - much appreciated.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
As @fanoush says, maybe you (or an app that use it) had enabled HID (which makes window 'grab' the device as it thinks it's a keyboard/mouse/etc).
Otherwise maybe enabling passkey pairing or something like that did it?