Topband: Spurious signal

[Pete - W2PM]

I know this is not directly 160 issue but have seen related posts and replies in past.  I am hearing the local NOAA vhf weather (162.55 fm) on 1641 khz in the AM mode.  This is on several receivers and antennas as well as car radio and seems to be fairly local as i cant here it on my remote QTH in eastern CT. 
Possible mixing product but the stretch is spectrum seems and also how the FM original signal can be heard in AM.  This isn't alope detecting either.  Audio is clearest dead nuts zero beat.  
Any ideas ?  73 Pete W2PM