Is CBP Actually Fining $5000 for SENTRI Lane Violations?

In 24 hours last week, I was contacted by two separate individuals who were fined $5,000 by CBP for SENTRI lane violations.  If this is a new policy, a $5,000 fine seems like way too severe a penalty imposed by CBP.  

Both individuals appeared to have similar fact patterns.  Neither party had a SENTRI pass.  Both individuals reported this occurring at the Tijuana/San Ysidro port of entry.  Both said that this was a third lane violation that CBP had supposedly recorded against them.  Interestingly, both individuals related to me that they had no idea that either the first or second incidents were actually recorded as violations against them.  Tijuana has a lot of roundabouts.   It is easy to get confused on the roads and end up back at the border.  I can remember an incident a long time ago driving into Mexico, purchasing auto insurance for a trip to Ensenada, and ending up right back at the border to enter the U.S. just minutes later.  The roads are at times confusing.  Both parties seem to have some confusion on the roads there resulting in at least one violation.       

I do not know what someone should do in this situation.  The fine seems to be out of line with the violation.  I think it would be worth it to fight the issue and/or ask for a CBP supervisor to review the issue, assuming you are someone who is facing such a fine.