I have the hatch on the same layer (default line weight) as the gray lines on the top and bottom if it, but it would appear that the hatch line weight is even smaller than the default also. 

It seems that the hatched section seems to import into illustrator as some sort of object. It doesn't tell me a line weight for that, even if I expand and try to select the lines themselves. The default line weight in illustrator is .709pt

It would seem that the change needs to be made in autocad prior to illustrator?