Fiance visa telephone interview

[Incy]

It hasn't been a long wait compared to some, we submitted everything on 12/11/18.
We have received emails requesting telephone interviews on 13/12/18.

I know I shouldn't be nervous about this, but given our circumstances, I am wondering why we have been asked for telephone interviews. I have read that they pick people at random, but our relationship is probably little different to others.

We are both male.
He is 21 and and I am 43.
We have only known each other since May 2018.
We met twice then he stayed with me for nearly two months before he had to go back to Malaysia.

Now, all of that wouldn't make one iota of difference if there wan't a visa involved, but it does make me feel a little paranoid about them not believing the relationship is genuine.
I guess I could send them the entire whatsapp chat log, but even I wouldn't want to read back through a chat log that covers every day, for hours during every day, since we met.

[Londoner007]

Not at all random, calls are made when they require further clarifications.

Your triggers would have been half your age, only met few months ago and from malaysia.