[Elecraft] Receiving AM on the K3 - Odd behavior

[Harry Yingst via Elecraft]

I noticed something odd when receiving AM.
I have the AM and the FM filter installed and both enabled for AM Receiving.
The manual states:In AM mode, the I.F. bandwidth required for good fidelity is about twice the AF bandwidth. This is why a 6 kHz or wider crystal filter is needed to effectively use the 3 kHz NORM setting. If a 15 kHz FM filter is installed, it can be used in AM mode to provide good fidelity at even higher AF bandwidth settings. 

Watching on The P3 as I adjust the Filter width between 1.3 kHz and 3 kHz it tracks properly but between 3 kHz and 5 kHz it's really only varying between 3 kHz and 4 kHz (with 4 being the max) 3 = 3 , 3.5 = 3.25, 3.5 = 4, 4.5 = 3.75, 5 = 4
I confirmed this by loading up Spectrogram and looking at the audio output and it tracks the same way.
To further test I went in to SSB mode set FC to 2 kHz and BW to 4 kHz then moved the shift  to 2.2 kHz and the output moved to 4.2 kHz and the P3 tracked it as well as Spectracom.
I also looked at the Spectracom display in FM Mode with the squelch open  and it appears that the audio stages could easily reproduce out to 6 kHz with little roll off and  even displayed out to a bit over 18 kHz.

Have others noticed this?