Slight misalignment of centre stamp footprints (columns 2 and 3) compared to columns 1 and 4. (0.051 mm vertical offset). This only affects double, triple and quadruple-wide stamps, and there is enough play in the M3 screw holes that this does not have any functional impacts.
Will fix in v1.1 or v2.
Stamp designation horizentally is A1, A2, etc, with the letter referring to the row, and the number referring the column. This is the reverse of what is conventionally used for a spreadsheet, and should be reversed.
Will fix in v1.1 and on other baseboards.