Gc without stamping

[jvs1]

I got my GC last week by mail along with the welcome letter (I-81). I had my interview last month (485). But the officer didnt stamp the passport (took out I-94)and said we will get welcome letter and gc by mail and if we want we can get the stamping. When we went for stamping with the welcome letter to the same local office the IO at the front desk said, we cannot be stamped without 485 approval letter (which we never got). When we showed her the GC she said our case is fine and we dont need a stamping.

Will this cause any problem while traveling - no stamp but have GC.

Thanks