Never had a vehicle do this, and it strikes me as odd, but maybe someone more knowledgable than I can shed some light.
My bike starts just fine, I usually start it with the choke halfway out and let it warm up for about 5 mins or so before pushing the choke in and riding off. Almost immediately after I push the choke in the oil light comes on. The first time this happened I freaked out and parked the bike, everthing seemed to be fine, restarted it and all was good.
Many rides later this happens every time I ride, oil light comes on and stays on for a good 5 minutes...then it will go out when I'm sitting at a light but come back on when I twist the throttle. another 5 minutes or so and it goes out for good and stays off the rest of the ride (unless I get up into the 10,000 RPM range). I checked the oil level and it looks, possible, a little low but seems fine.
Any thoughts? It just worries me.