Harvard grad and US Senator Al Franken was at MIT on Friday to see his son Joseph graduate from the MIT Leaders for Global Operations program. Joe earned two degrees — an MBA from MIT Sloan and a master’s in engineering. . . . Dave Matthews and his band have been spotted around the Ritz-Carlton, Boston Common this week. The band should be long gone by now; it had a gig in Saratoga Springs, N.Y., on Friday.