Hello Ed,
Yes, I have noticed that also, but I don't take too much notice of it, if I want to monitor either my CW or SSB signal then I just turn the Level down to -30dB and that gives a better indication of the signal, but don't forget to turn it back up on receive. I guess that the transmit monitor for the display is picked off the transmit path somewhere and is overloading the receiver, I get exactly the same affect on my SDR receivers if I overload them.
I tend to use a separate receiver to monitor my signal if I need to anyway.
73 Paul.