Yes, the fact that 0 is returned ~1% more often than other digits is very significant. E.g. if the generated random number stream were used for XOR encryption,

Yes, the fact that 0 is returned ~1% more often than other digits is very significant. E.g. if the generated random number stream were used for XOR encryption, then you could just collect a large number of encryptions of the same text, for each character look which one occurs most often and then that would be the encrypted character (because 0 has a bias and occurs most often and c XOR 0 == c). Using other encryption methods the advantage is often not so obvious, but it exists. Also it should be noted that 1/250 is a pretty large bias and would probably not even need particularly many ciphertexts.