[Steve DeRosa]

The L-48 was usually made from a combination of laminated mahogany top/rims and maple back - which, interestingly enough, resulted in a reasonably good-sounding guitar for the money (FWIW upright bass players had discovered the tonal/structural merits of laminated instruments a couple decades earlier); the use of spruce in the earliest models may in fact have resulted from Gibson's attempt to clear out existing prewar/wartime L-50 bodies - FWIW there are also supposedly some extremely rare, solid-top postwar ES-125 electrics out there (which Loar copied with their LH-309/319) - in which case the tops would indeed have been carved...

An alternative scenario is that the laminated mahogany top would serve to visually distinguish the L-48 from the L-50 (LP-style trapezoid markers would not be adopted on the latter for a few years), and/or that the laminated spruce top did not provide the tone/volume Gibson was seeking. Inasmuch as the competitor Guild A-50 would be introduced with a laminated maple top (a number of contemporary low-end archtops also used laminated hardwood tops - often birch - and the laminated spruce-top, entry-level Gretsch New Yorker was generally regarded as acoustically inferior), there's a certain logic to the argument - unfortunately, at this point in time the only evidence for either position is anecdotal and apocryphal at best...