That horrifying "clicking" noise

I have just noticed that when my bike has a cold start (either when it sits for a day or two, or when I start her at night), that if I give it a few revs, I hear a very faint cicking that is syncronized with the engine RPM (hope that makes sense). This occurs in the 3,000-6,000 RPM range (thats at least when I hear it). After the bike is all warmed up to about 150+ degrees, I rev it up and the clicking noise seems to go away. I rode it a few days ago with a 48 hour "rest" in between rides, and noticed it then. Also noticed it tonight when it was sitting at the little ladies house all night after I rode it today. I had to actually use the choke for the first time, or the bike would crap out. Every stop sign on the way home I gave it a rev or two to see if it made the noise. Realisticly, I dont think it was. But by then my mind started playing tricks on me. When I got home and rode in the complex parking lot, I cruised in at 3-6k RPM range and heard nothing. I have never before heard this noise, until I have had a few true cold starts. Is this something I should be worried about? :help: