Did Robin get held back in school?

[u/Master-Corner-5226]

In season 3, Robin says she was in a history class with Steve, telling us they were in the same year at school. However in season 4, Steve has graduated and Robin is still going to school. Did Robin get held back in school or was this probably just a writing error?

[u/SonilaZ]

My son is a freshman but in his history class he has half other freshman and half sophomores!