....When I look today the option for these free points is there again but then if you click through to it, it says I've already redeemed for this award "this quarter", so I guess every 3 months there's a new free travel offer.. or at least that would be my guess based on the wording regarding "this quarter"...
Maybe you've never realized this before, but each reward has its own limitation on the frequency with which you can redeem it; for example:
Redemption of Club Carlson Gold Points is limited to one (1) redemption per calendar quarter, per Club Carlson account and/or e-Rewards member account.
You'll see this message when you click on the 1,000, 2,500, or 4,500 Carlson Goldpoint rewards.
(However, some rewards may have no such limitation.)