Endless CAM messages with recent CURRENT

Today I updated my 9.0-CURRENT system (amd64) to revision 199506: After 
rebooting I get the following messages two times per second in an 
endless run:


---------------------------------------------
...
Jan 14 09:37:47 krabat kernel: (sg1:umass-sim0:0:0:0): 
cam_periph_release_locked: release 0xfffffe0009f41200 when refcount is zero
Jan 14 09:37:47 krabat kernel:
Jan 14 09:37:48 krabat kernel: (sg2:umass-sim0:0:0:1): 
cam_periph_release_locked: release 0xfffffe0009f41100 when refcount is zero
Jan 14 09:37:48 krabat kernel:
...
---------------------------------------------


sg1 and sg2 are devices from my front panel card reader Silverstone 
SST-FP35B:

#camcontrol devlist
[..snip..]
<Generic STORAGE DEVICE 9744>      at scbus6 target 0 lun 0 (sg1,pass3,da0)
<Generic STORAGE DEVICE 9744>      at scbus6 target 0 lun 1 (sg2,pass4,da1)


Is it possible that the last changes in usb code (xhci) or in cam code 
are responsible for this? Does anyone else observe this behaviour?

Please let me know if you need more info or if I can test something.

Thank you for any hint,
Rainer Hurling