Of course maybe he just didn't want the accompaniment. If he was trying to play along weith you without getting in tune with you, you'd have a right to object. If he wanted to play without you joining in, that's his right as well, and that shouldn't be seen as unfriendly.

It's quite true that traditional musicians often tune their instruments a bit sharp of concert piutch. Sometimes fixed pitch instruments aren't quite in concert pitcxh either - that's why electronic tuners provide an option for changing the pitch they are set at.