How long have you had the car for BMWRP8? I remember that by disconnecting the blue temp sensor also tricks the car into doing a warm start. The only trouble is, this makes the car difficult to start when warmed up for some reason. As you're having no start-up issues I can only assume that all is well - it sounds like your idle system is working properly - high idle when cold, normal idle when warm.
HTH,
Shaun M