SNMP reporting 10Mb interface speeds on 4x1Gb LAGG VLAN interfaces

[jim12345]

Hello, I'm running a Netgate SG-8860 HA pair on 2.3.4-RELEASE and am trying to get interface stats.  Our configuration is as follows:

igb1 (WAN) == WAN
igb0 (LAN) == HASYNC
igb2,igb3,igb4,igb5 == LAGG0

Then off of LAGG0 I have a number of  VLAN interfaces, 10 at present.

Both MRTG and a standalone Windows MIB browser (SnmpB) report the LAGG speed as 4Gb/s, which is what I would expect.  I would ALSO expect each of the VLAN interfaces to report the same, 4Gb/s, however they are all reporting 10Mb/s.  I am running the SNMP polls against the CARP VIP and the results are the same regardless of which cluster member is currently active (i.e., I tested in a failed-over state and got the same results).

11: ifSpeed.11 4000000000
12: ifSpeed.12 10000000
13: ifSpeed.13 10000000
14: ifSpeed.14 10000000
15: ifSpeed.15 10000000
16: ifSpeed.16 10000000
17: ifSpeed.17 10000000
18: ifSpeed.18 10000000
19: ifSpeed.19 10000000
20: ifSpeed.20 10000000
21: ifSpeed.21 10000000

Is there something I'm doing wrong?  Or are my expectations incorrect?  Or is there a bug someplace that's reporting incorrectly on VLAN interfaces?

And lastly, I'm hoping the answer is No, is there any reason to worry that the VLAN interfaces might actually be limited to 10Mb/s?  I've run speed tests and gotten much better than that so I'm pretty sure it's just a reporting issue, and not an actual limitation on throughput, but I have to put the question out there.

Thanks!