Re: X-MEN: FIRST CLASS - Grading+Discussion **SPOILERS!**
I think you missed the point of Sammy's joke. I think he was stating that the cashiers were thinking "X-Men: First Class" was a Wolverine movie.
In this question and answer article Singer clearly states that "X-Men: First Cass" is a prequel.
Chief of Operations
Ignoring the The Last Stand since 2011.