Majority committed replication lag spikes after an election

One of my scripts for testing Flow Control prompts an election. I've noticed that in some runs of the test, there is a spike in reported lastCommitted lag that occurs immediately after the election. This spike occurred both when the election chose the same primary as previously and when the election chose a different node as primary. Flow Control is a consumer of lastCommitted lag, so it will respond to the spike and throttle writes. I don't see why lastCommitted lag should have a reason to spike, particularly if the same primary is elected, so I believe this behavior should be investigated.