comparing traffic between 2 NFA

Hi, I have the following scenario:

I have a frame relay connection with my corporate headquarters, I also have one NFA in both side of my link and I'm comparing the traffic IN/OUT in the interfaces of both routers. I see there are some differences I explain you below.

Standing on Traffic Tab (last hour report) on the corporate NFA I see this:

Total Max Min Avg 95th
Traffic IN 17.18 MB 183.01 Kbps 7.88 Kbps 38.18 Kbps 78.16 Kbps

Traffic OUT 116.11 MB 622.74 Kbps 22.4 Kbps 258.03 Kbps 578.02 Kbps

And standing on Traffic TAB (last hour report) on NFA (my NFA) I see this:

Total Max Min Avg 95th
Traffic IN 99.71 MB 596.08 Kbps 22.38 Kbps 221.58 Kbps 496.19 Kbps
Traffic OUT 17.1 MB 182.58 Kbps 7.43 Kbps 38.01 Kbps 78.3 Kbps

You can see the big difference in the traffic from the corporate router to mine. I've seen even 160 MB of difference in this traffic (from corporate --> my router). So I'm confused and I want to know if it's normal o not?

Notes: both NFA are 5.5.0/5502, NFA server and routers have the same time and both routers are configured the same way.

regards;
Israel