Does an event thing pop up everytime someone gifts you an item? because something from my wishlist popped into my inventory, but I didn't buy it and I didn't see an event thing popping up saying so and so has sent you said item.

If it was sent to you from someone, yes.

If you got it from a random event, then no.

Or, are you doing quests at the moment and didn't see the prize, by chance?

Not doing any quests at the moment or anything. it's happened before to I got patriotic jeans, I didn't buy them and wasn't doing quests at the time.

are the prize for

(the achievement you just got)

ah thank you! makes more sence then. was so worried 'cause they randomly popped in my inv and I didn't buy them lol

No problem :)