[Elecraft] K3 slightly off frequency

[Steve Wilson]

A few of us in Fremont, CA have a weekly 10 meter net. I have a friend with a K3 who always sounds off frequency. When I use my K3, I've been told that I am off frequency. There are a couple of KX3 users who don't seem to have a problem. When I use my Kenwood TS-590 I seem to be on frequency.
Is the K3 known, in general, for being slightly off frequency? 
Thanks, Steve  KG6HJU