As far as I know .02 is the payout cutoff, and it should have paid out. @freebornangel is considerably more intelligent, and informed about this, than am I, but I do recall he mentioned that different apps report pending payouts differently. .021 is very close to the .02 dust threshold, and this makes me think that it is reported via the source you checked differently than it is calculated by Steem.

You did not provide the screenshot, nor do I recall which apps over or under estimate payouts. Maybe Steemworld overestimates them. You should know that I barely claim rewards LOL, so I am not the most informed party you could be inquiring of on this issue.

Personally, I'd provide @freebornangel the screenshot, and ask him. I reckon him honest as well, and he does appear to hold you in as high regard as do I.

Hope that helps.