Strange behavior in CCNP:Switch lab

This is just weird (and maybe I should be in one of the Rack-rental subfora, if so, sorry).

I have been working my way though the lab workbook tonight, and on loading the config for lab1.4, I imediately see the following output on my console (I have only included one sample of identical syslog outputs and config stanzas, however I see the same messages from all the inter-switchlinks):

Switch-1

*Mar 1 00:25:02.785: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/10 (3), with Switch-2 FastEthernet0/10 (2).

(Same message for all 6 of the interswitch links):

Switch-2

*Mar 1 00:18:07.663: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/10 (3), with Switch-1 FastEthernet0/10 (2).

Switch-3

*Mar 1 00:18:11.435: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/15 (3), with Switch-1 FastEthernet0/15 (2).

So one would think that the switches are simply mis-configured.. but this is not so! All the ports have the same base config (which was carried over from the last exercise, 1.3:

interface FastEthernet0/14

switchport access vlan 2

switchport trunk encapsulation dot1q

switchport mode dynamic desirable

switchport trunk native vlan 3

I finally resorted to simply returning the native vlan to vlan 1 (with the command no switchport trunk vlan 3), which worked. But this makes no sense at all. Any thoughts? And again: I had made no changes to the config supplied by INE with the 300-115 Workbook. I don't get it. To put it mildly.