Random $45 credit appeared on my CC

I was paying bills yesterday and noticed a random $45 credit on my CC from WS. I have no clue - the itin in August is long past and I have nothing booked until Iceland next July. It isn't tied to any correspondence I had from either WS of my TA (who I won't bother over a small credit - had it been a bill I'd have called..."

Clueless...

Windstar error in your favor 💰. Sweet

All kidding aside, I am also clueless. If I had to guess, I would say it might have to do with a refund from port fees or taxes being less than anticipated.

Sent from my XT1575 using Tapatalk

My best guess is that it's a refund for the small onboard credit we had left in August but those aren't supposed to be refunded.