It's up to 80% at 1,000 cycles. Your's is showing nearly 90% which could possibly be a little low for that cycle count. But to be honest it's completely within tolerance (And there's a lot of other factors that could throw that estimate out). You could try talking through it with Apple, but unless the device is severely crippled in the battery life, they likely won't be able to do much.
What makes you bring it up? Is the battery only lasting a few hours? I wouldn't get panicked by software estimates if that's just the case, their notoriously varied in accuracy.