Here's an experiment to try:
Remove the reflector and also the inner core from the housing. You'll notice that there are feet on the reflector to stand it off from the LED some minimum distance.
Hold the reflector in front of the LED and point it at the wall close up with the feet against the LED board. Observe the beam pattern.
Start moving the reflector away from the LED until you observe a similar pattern as your original cloverleaf. What is that distance between the LED and the reflector?
In my case, I had to move the reflector away by a few millimeters. "Hmm..." I say to myself. "That's about the thickness of the O-ring." So I put the reflector in the housing without the O-ring nor the screw-in retaining ring, hold it there with my finger and insert the inner core. I was seeing if the LED carrier/star pushed against the reflector and it didn't really feel like it.
So, it seems to me that the housing can be reassembled with the reflector in first, then the O-ring, then the threaded retaining ring. I tried that and got rid of the clover artifact, however, that adversely affects the water resistance, so I put it back the other way.
I figure that if it really annoys me, I'll mill an aluminum or copper spacer to screw in behind the LED carrier/star to shim it out properly.
So, @David Hilton, yeah, there is some shimming that can be done to bring the reflector closer to the LED, however it's not really fine grained on the order of a few thousandth of an inch, but more like a few millimeters.
If you don't want to go through that much effort, at least you can try to get a thinner O-ring with the same diameter, or cut some gasket material to minimize the distance as much as possible.
PS: Oops, I noticed that the O-ring doesn't really have that great of a seating surface, so I'm not too sure how well a gasket will work while still preventing water intrusion. Since there is a smooth, flat section between the O-ring seat and the retaining ring threads, I might go with a thinner O-ring sandwiched between the threaded ring and the reflector if I could get enough of a bevel on the threaded ring (on the outer, threaded side, not the inside) to force the O-ring against the walls of the housing.
Aw, how am I kidding, I don't really need that great of water resistance. I'm reassembling it with the O-ring on the outside. Now to do a beam comparison with the reflector in each of the two positions...