Bodging my way through life

A disturbing number of times in the last few months, when I've tried to pump gas, the nozzle will just shut off quickly. I've tried various depths and angles of insertion*, holding the valve by hand, using different latch positions, but it keeps just shutting off. This has happened a multiple gas stations as well. I don't think I've forgotten how to pump gas. Is this happening to other people too? Or is it time to investigate the ventilation on my gas tank?

* Why does this make me think saucy thoughts?