[Elecraft] K1 STP shift?

[rhulett1 at comcast.net]

After my K1 had been idle for a few months, got it out this weekend for the SKCC sprint. Surprisingly, no responses to my calls, so checked transmit frequency with another receiver when pitch of a signal received on the K1 was 600Hz , found transmit frequency was off by about 400 Hz.  Opened the K-1 up, set the switch to test, sure enough the test note was about 200 Hz.  Adjusted C13 to bring the pitch to STP, 600Hz, closed up, now transmit frequency is on the money and my calls are readily answered.

My question, would this indicate a component beginning to fail?  I'm surprised that any C13 adjustment was necessary ever.  Up until this, everything about the K1 has seemed pretty rock solid.

73, Curt KB5JO