Question regarding my newly bought Louisiana vertical smoker.

After trying out my smoker yesterday, I had an issue that I've never had with my previous vertical smoker (Pit boss)

Upon reaching 400F the smoker seemed to struggle to maintain the heat as it was going from 390 to 400, but I wasn't too surprised by that, but after about 10 minutes it just stopped.

The blue light on the ON button was still alight, but the fan completely shut down.

I didn't notice if it maintained its temperature because I had a panic moment and had to switch out my food into the inside oven.

I contacted the seller and they told me that was normal, that upon maintaining its temperature for a while the fans would stop because the ambiant heat was enough without wasting pellets.

Now I'm wondering if I'm being bullshited by the seller or if that's actually the case.

I would try it today, but it's raining buckets so I can't.