Looking for documentation on these messages in syslog...

I have a VC'd pair of EX 3400s running 15.1X53-D56 (fpc0) and 15.1X53-D58.3 (fpc1), and I'm getting a bunch of these MAC adds/drops (sensitive details omitted):

dc-pfe: LBCM-L2,pfe_bcm_l2_mac_delete(),848:l2_mac_delete: Iterating BCM units: 0 hw-tok 4 mac= 10:62:E5
fpc1 LBCM-L2,pfe_bcm_l2_mac_delete(),848:l2_mac_delete: Iterating BCM units: 0 hw-tok 5 mac= D0:27:88
dc-pfe: LBCM-L2,pfe_bcm_l2_mac_add(),735:l2_mac_add: BCM unit: 0 hw-tok 4 Success add mac= 00:1C:25
fpc1 LBCM-L2,pfe_bcm_l2_mac_add(),735:l2_mac_add: BCM unit: 0 hw-tok 4 Success add mac= 00:1C:25

They seem to be running primarily on fpc1, but I'm wondering if there's any documentation on what these messages are.

I need to get the switches on the same version (clearly), but is this expected behavior?

Any further reading would be fantastic. 

Thanks. 

edit- missing word or two.