Agaro moka pot help

Hey, I just got this today and did a trial with a slightly coarser than moka pot grind. The coffee came out smoothly but there was not crema (which I expect with the coarse grind). At the end though, when the bubbles started they came out really fast.

Before I even had the chance to turn the heat off the bubbly coffee almost went out the top of the pot.I thought this was not supposed to happen with the valve in place.

Is this a problem with the valve and should I return it? Or is it just cuz I overheated by mistake.