Assuming 9 needs to be just to the right of 999 (and not handling the last column at all), I would probably do this as follows:
conditionFail = Z(:,1:end-1)==999 & not(Z(:,2:end)==9)
It is possible to put all the code into if statement (without needing to pre-specify the condition), like this ...
if any(any(Z(:,1:end-1)==999 & not(Z(:,2:end)==9)))
but I think that is more obfuscated.