question about PSA authentic grade on 1961 Fleer basketball

I just received some grades from PSA for a couple of 1961 Fleer basketball cards that I submitted. Two came back as "Authentic." No mention of either of them being altered. What does this grade mean? Trimmed? If they were trimmed, I assume they would not have been graded or else would have graded "Authentic Altered." Smaller than minimum size? Or what?
Always looking for Mantle cards such as Stahl Meyer, 1954 Dan Dee, 1959 Bazooka, 1960 Post, 1952 Star Cal Decal, 1952 Tip Top Bread Labels, 1953-54 Briggs Meat, and other Topps, Bowman, and oddball Mantles.
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Comments
Straight from the PSA website:
N-0 Authentic Only - This means that PSA is only certifying that the item is genuine, without a numerical grade. This may be due to the existence of an alteration, one with malice or otherwise, a major defect or the original submitter may have requested that PSA encapsulate the card without a grade. The "Authentic" label means that the item, in our opinion, is real but nothing more.
I wish PSA would offer an explanation when they simply certify items as "Authentic", even when they put "Altered" on the label.
It would be nice to know what they saw that prevented the card from grading. At least on cards with a certain potential value, say over $100.00 or over $250.00.
If it was trimmed or colored, I would think they would just not encapsulate it. Previously, I have received cards back that they did not encapsulate due to "trimmed." I didn't request encapsulation without a grade. Since they encapsulated it, I would have thought they would have put "trimmed" or "colored" or whatever. Oh, well.
Always looking for Mantle cards such as Stahl Meyer, 1954 Dan Dee, 1959 Bazooka, 1960 Post, 1952 Star Cal Decal, 1952 Tip Top Bread Labels, 1953-54 Briggs Meat, and other Topps, Bowman, and oddball Mantles.
Post a picture so we can see if anything jumps out that you might have missed? A lot of these have off center backs, might have played a role.