net.data error Incorrect symbol

We started getting an error sent from net.data that has "Incorrect
symbol <varies> encountered in macro <varies> at line <varies>" If we
restart the Apache server right away when we catch this the error goes
away without making any changes to the macro or any of the includes
(just about all of our macros have includes) so we can prove it's not a
constant error. The errors will start at random times and then go away
by themselves. We were able to force it to happen by putting an error in
one of the includes (add an extra @) and then taking it away again. No
errors in any logs (that we can find). Anyone else come across this
error before?