How do you think that the change could be accidental?
Copy and paste from pior editions, copy and paste from other Cavalry units, copy and paste from the basing sheet, or literally just not changing anything at all would have resulted in the 60mm base as mentioned.
Someone would have had to have gone in and deliberately change it, which strikes me as something that is unlikely to happen by accident.
"Hey guys, I accidentally had the app open in edit mode, accidentally clicked on the 60x35 that was already there, and accidentally typed in the bases that just so happen to be the ones the unit is actually sold with in it's only current iteration."