Contact being blocked without my knowledge

I wanted to find out whether it is possible for a contact to be blocked
without my knowledge.

One of my contacts claims to be blocked by me but I have not done this and
I do not see any changes to this person's profile from my end. This contact
does not see my profile picture, timestamp or status, which indicates that
this person has been blocked by me. Could this be a fault of the
application or the phone? Should I ask this contact to re-install whatsapp
on their phone or should I re-install it on mine? Or should I check that
this contact has not been placed on my blocked list?