What Gavin said. Maple has closed pores (so not really pores at all then) unlike some woods like mahogany which have large open pores and do need filling. The only areas that may need some filler are round the edges by the binding if there are any small bits of end-grain that have caught on something then come away and left small holes.

Beware of glue marks on the veneer, especially along the centre join and round the edges. Use metho or turps (not water) to wipe on the veneer and see if there are any light areas of glue that aren't absorbing the fluid. If so, you can try sanding them down and using a wire brush on the area to try and loosen the glue. If that doesn't work, you can try Goof Off adhesive remover. There are very few stains that will work on glue, so it needs to be removed right at the start.