1951 Topps Teams & All Stars

[Volod]

This is an old thread, but I just noticed in looking at my 1951 Topps team cards that my undated White Sox card has an inverted back. That is, the reverse has the correct roster, but it's upside down in relation to the obverse.
I would have posted a scan, but, obviously, this anomaly can only be appreciated from seeing the card itself. So, I'm scratching my head and wondering: did Topps put the sheet in the press upside down, in which case this particular card was lucky enough to have been in exactly the right position to receive the correct obverse - just upside down? But that seems way too unlikely, the odds favoring another team on the obverse. Also, if it was not uncommon for sheets to be printed upside down, it seems that inverted backs would be rather commonplace, but I don't recall any mention of this in my readings on the set.
That would seem to rule out the alternative possibility of a printing sheet composed of just one team, wherein all cards had inverted, albeit correct, rosters on the reverse.
So, does anyone have any thoughts on an explanation, or does anyone else have cards with inverted backs?