this skype person is very confusing

So today at 22:33 a guy called Hassan on skype just called me without any reason.

https://gyazo.com/ccb26d3eb93170c63d5752e72f4d2ac4
I have answered the call and asked him "how do I know you?" and he replied "we were playing oldschool runescape together a long time ago". Also than he ended call and replied "dont worry", now this is very confusing to me because I knew every friend/clan member that has added me on skype and I do not remember adding this guy.
Do you guys have any idea what he ment with "just answer so i can print screen as evidence for my work" ?
Also I do not remember adding him on skype...