It's my fault. I've been after a nice copy for 20 years and passed on any number of lesser copies - several on Heritage in the recent past. It's certainly my favorite of the ones I don't already have, and the only Whitman Planet cover I now need. But overall I think I prefer #71, #72 and Man O' Mars.
So I kept a lot in reserve and didn't bid on a lot of others I might have to make sure of it. I thought it might possibly hit $1500, and I put way more than that on it via proxy.
For a few seconds I was winning at around $850, then it just took off and kept going.
I suppose it's because it's highest graded, but at 7.5 that status is vulnerable.
As for #71, I'd say that one went for about double what I'd've expected. Anyway, here are my Whitmans, sans #66. (I'll get that sucker one day!)