RX antenna choice and noise floor

I am using my 8 ele 6M yagi on port 2 of the new 8600. Because of my fairly high 6M noise levels the meter usually sits on -102db….. I have noticed since adding a 6M vertical dipole for RX (noise reference) on RX B that when I select the RX antenna as RXB I get a noise floor of -109 on the S meter. HOWEVER when I switch back to the ANT2 receive position the noise floor does not return to -102dbm but stays at -109dbm. Is this a flaw in the firmware? This is locked in whether I reboot or not unless I start on the ANT2 RX position then it stays on 102dbm until I try the RX B receive antenna choice. Anyone else see this? I have not reported it yet to Flex.