Siglo IV question

[Cello]

Hey again, 

I have a question about a Siglo 4 I recently received from a friend. The cigar and the band didn't give me much concern as they both looked good. But then I decided to test out my new black light. I compared the band of the new Siglo with 2 COROs I bought here a couple years ago and a Siglo II another friend picked up in a duty free.

The Sig 2 had the 4 dots and the chb code, the Coro had the chb code, but no dots, and the Sig 4 had the dots, but no chb code. All things I've read that aren't outside the norm. But when I compared the yellow on the bands under a black light, the Sig 4 was a different color than the other three bands. I've attached a couple photos. The Sig 4 band is the one on top of the Sig 2 band.  Should this be concerning or is it normal?