How does the netiq rest driver works with oauth as authentication protocol?
Are you using the latest REST shim (version 188.8.131.52)? It had some fixes in this regard (Additional logging is provided to show REST URI validation calls )
IIRC the driver does call the remote API and if that return a 401, then it will refresh the token. So the frequency will depend on token lifetime and the amount/interval of events that need to be processed by the driver.