I hope you took a screen shot of the webpage when you bought it.
The page I bought from used to say the seller paid any and all tariffs. It doesn't say that now.
I haven't' been out o the country in a long time... When you take your drone out and then return and bring it back in, is there some sort of paper trail you are supposed to keep with you demonstrating you took it with you on the way out?
If not...