I think the problem is that once you "see" it... you can't "unsee" it. Every time you look you see the same thing.
Everyone's brain works differently, I know my brain sees patterns easily, geometric patterns, number sequences, etc. So to me it just leaps out. If you see the colours together, it's not as clear, one of the "arms" is a different colour. But because I see the shape first, the colours are secondary.