The advice already given is good. The levels in the heads of
combination squares aren't usually that good. Another thing to consider
is the length of the reference surface on the level. I don't know what
sort of orange level you are talking about but if it has three vials,
it must be longer than the face on the combination square head.

The orange level may report a level surface but keep in mind that could
be just between the two ends of the device.

If you want to confirm what your first level told you, you use another
level of the same length.

If you want to adjust the wing with the table, you should be using a
different measuring device. A level, even an accurate one doesn't have
a very high resolution.

If you are concerned about the wing sagging or riding high out at the
ends you should use a long, accurate straight edge and reference off
the table. Better would be two used as winding sticks to see if one
corner is higher.

If your concern is the wing being level with the top right at the seam,
a dial indicator on a base would be an appropriate tool.

G'luck.