Guild Wars 2

I’m honestly not quite sure if this is a bug or not..
I only noticed this today, but whenever I sell something in the TP, 2 seconds after, I hear a really weird sound.. I can’t really explain what it sounds like, but i’ve never heard this before.. It’s like a ’’byooong’’ sound, kinda lol

Not sure if it’s supposed to be like this or not (?)

That’s your mail carrier’s sound effect

Even if I don’t have any special mail carrier on?.. I just have the normal one..