[Elecraft] K3 & KPA500 Spike in Output Power

[Peter Quick]

I have fairly new K3 & KPA500. They both are running the latest
software. When on CW I typically call a station with my RX filter set
at 2.8kHz. If there is an increase in noise level, or other adjacent
signals I will switch receive BW progressively from 2.8kHz to 1.8 then
400Hz. When I then resume transmitting I notice that I will see what
appears to be a power spike on the wattmeter on the KPA500 from 500 to
700 watts for one or two dits, then drop back down to 500 watts. The
fault light does not flicker or come on when this happens. This never 
happens when switching to 250Hz. It consistently happens when going from 
2.8 to 1.8 and from 1.8 to 400. All filters are from Elecraft and are 8 
pole.

Have others seen this and is it normal?
Is there a problem with this?
Is it an actual spike in power from the K3 resulting in a spike from the 
amplifier?

73 Peter VE3SO