Low idle during warm up

I have a 2002 R1. It starts easily, and the initial engine choke sets the idle slightly high as normal for warm up (say 1400rpm). When the bike reaches about 50 degrees (give or take) and it has come off the choke setting, the idle drops down to about 800rpm, and I have it set at 1100 rpm usually. Once hot i.e. 72 degrees plus it idles correctly at 1100rpm. It just seems to be low during the warm up stage. This has only started happening over the past 2 days. Any ideas? cheers, TheOoz