JWT signature does not match locally computed signature

I am using

JwtBuilder builder = Jwts.builder()
                    .setId(user.getEmail())
                    .signWith(signatureAlgorithm, signingKey);

to create a token then

Jwts.parser().setSigningKey(secret).parse(token);

to authenticate. When I run this in a JUnit test, it works fine. However, when I authenticate token passed as a header over REST call, authentication fails with SignatureException. I have verified the token on both ends of the HTTP call and the token string is identical. Code to create/authenticate is static, therefore, the secret is same on each side. Any clues