QCass

If I am applying to graduate school 10 or so years after finishing undergrad, and I have in the meantime been working in a related field, is it frowned upon to have all of my letters of recommendation be professional in nature (past bosses, supervisors)? I unfortunately never got particularly close with any professors while an undergraduate, and I doubt any of them would have anything meaningful to say about me at this point. This is in mathematics, if that helps at all.