I think you will get your dough. Since I work for a university, it sounds like someone in the system did not understand what the fark they were doing. POs are required when a price exceeds a certain dollar figure. Unfortunatey, they may have tried to pay you via check and found out they had to submit a PO. I would be pissed, but I do believe you will get paid in a couple of weeks.
FYI: At my institution POs are required when a price exceeds $2500
Peace and Smoke,
My Weapons: Custom rig - Kandi, UDS; Bubba Keg; 22.5 WSM x 2; 18.5 WSM; BWS extended party; BWS Gator and an Onyx Oven; 29' ft Coachmen Leprechaun (Lola).
Dan Chambers get well soon, so we can tell you to "Shut up Chambers"