This sort of question is impossible to answer, unless you are able to determine the exact cause of the failure on your two machines.
So you will have to determine whether the 27 machines built correctly by testing one of them and checking to see if it boots up OK. Then try one of the failed machines showing a decompression error and see how it boots up.
If the test machine of the 27 boots OK and the test machine of the two failures does not boot, then I would think it fair to assume that all 27 were unaffected by the problem seen on two machines.