Corrosion around some letters on a Nike+ Watch

Hi! I bought an Apple Watch Nike+ 42mm on Christmas 2016. I just noticed some aluminium corrosion around the Apple logo on the back, on some letters and around one of the bracelet release buttons. Same thing on the Digital Crown. I live in a very humid and salty part of Northern Italy, near Venice, at 100m from the sea. I never use my Watch on salty wate, and I wash it at least a couple times a week with tap water. I’ve seen some much worse corrosion on the Internet though...

Do I need to worry?

Thanks for your help, and sorry for the crappy photos