advice Contacted by startup company/person

[Branded Domains]

Hi every one...today I got a call by a person (the mobile number of the caller was private) offering me $100 for one of my .com domains.I thought someone might be joking...but he said he is starting up a company and he got my no thru whois...I told I cant sell that for $100..I asked him his social profile contact..he said he will contact me if needed and disconnected my cal...by saying thank you..
So what that call was for verifying my whois contact or he is really want my domain.???
Please help me out what to do if he contacts me again