Dropping EAPOL frame, not key frame

[Norman Elton]

We have wireless clients doing MS-CHAPv2 authentication against our
access points. FreeRADIUS serves as a proxy between the APs and our
domain controllers. When a Mac laptop connects, or in some cases
roams, we see the wifi icon laddering up and down for 20-30 seconds.
During this time, I've spotted the following error in the laptop's
system.log:

inputEAPOLFrame: Dropping EAPOL frame, not key frame

Initial Googling hasn't turned up anything relevant, and I realize
this is likely not a FreeRADIUS issue (as it's only a proxy). But I'm
hoping that the collective wisdom of FreeRADIUS users could shed some
light on what's going on.

I'm comfortable wiresharking this to death, but my EAP knowledge is
somewhat anemic. Can anyone shed some light on what's going on here?

Thanks,

Norman Elton