That was the same with my plant previous bloom (previous winter) when I bought it in bloom. Sounds like you have the same plant.
This year every bloom has the pink blush... just inspected my plant in high light, and guess what
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The oldest blooms, now at least 7 weeks on the plant, don't have the pink blush anymore, also the green in the center has faded, hardly visible. It still has some pink showing on the petals/sepals, which is more prominent in the blooms that opened later. Last year it had some pink on the petals/sepals too but not as clearly as this year, however I didn't spot it on the first blooms that opened, when they opened. Seems that for my plant the blooms become more evenly white when they age.
Nicole