Thank you all!
A little update; I e-mailed him about this, telling him that I checked his work and noticed my name is missing, 'whats up with that' and so on. Previously before I noticed this, I shared author's Facebook post where he told his work has been published. Obviously in good intentions, giving a shoutout to someone I had worked with.
I wanted that there is some mark about this on social media as well, so I came up with this - I commented on that sharing post, roughly translated "Seems though that the maps are missing my name, shame. But they are definately mine.
"
One thing I just don't understand; I was asked to make a colored map but he has also solo'd to make black&white out of it (which looks awfully flat). Guess he didn't want to pay for the work of both... From now on, sharing psd. is definately off the table as a standard approach.