yeah, I've come across that so many times. The POs have stopped carrying such basic supplies such as packing tape and pens for everyone's use because there are those out there who take advantage of the service. it is so sad. The only tape they have behind the counter is the Priority tape and if you're not shipping Priority you can't use it.
I'm glad you got it figured out though, I can only imagine what the lines are like at the PO these days
