Is it normal i'm an unwitting douchebag?

I'm pretty slow on the uptake socially.

At work a guy helped me put away pallets. I rolled some over with a jack, then, while stacking more on top, he told me to leave them there and he'd take care of them.

He asked me next if I still needed the jack. I did, so I said yes, and immediately pulled it out from under the pallets and left.

Problem is, the stack wasn't quite where it was supposed to be, and thinking back, I realized he needed a jack to move them. I should've left it under the pallets and gotten another one.

I didn't realize my mistake at first, but as I was leaving, another employee gave me a long look, so my synapses started firing to figure out what I did wrong.

Frick.