Randomly got $10 membership for free

Ok, so I was talking in a GC and I was going to put a emoji in, and I suddenly noticed I could put server emojis in, I went to my nitro page and I suddenly have the $10 membership

I checked my bank account and no charge has been added

I never put a free trial

And I never was gifted it

What makes it strange is not even 3 hours ago I didn't have it, is this a issue I need to worry about or am I just lucky?