That sounds fairly normal. I have bolted a sacrificial board on top my 4896 that I then run a surfacing pas over to level the table. Just make sure the table is level before you install a board just to make sure the table is not skewed in any way. For my spoil board, I use 3/4" mdf that you could buy at home depot or lowes for about $25. A spoil board saves the special pads from getting chewed up and will also help in mounting fixtures to your table.
http://www.glenspeymillworks.com Techno LC4896 - 2.2Kw Water Cooled Spindle | Moving Table Mill from Omis 3 CMM, 500Lb granite base | Epilog Legend 32 Laser Engraver