Having a single router change is relatively (very) normal, and could be related to load balancing.
The best thing to do for this hop is probably to set up a route change exclusion - which will stop this standard oscillation from signalling a route change (having one normally oscilliting router can make it harder to find *real* route changes, because of the overwhelming volume).
To set up an exclusion, just right-click on your oscillating router and select the menu option "Add Route Change Mask". This will set up a mask that excludes the changes happening on this router. Note that this doesn't take affect until you reset your data, so after you add the route mask, just right-click on the Start/Stop/Resume button and select "Reset and Restart". Now, future "oscillation" on this router won't signal a route change (although other changes will).