Thanks for the reply. I forgot to mention that ALL flights (including my original 30 minute connection) were displaying on United.com as $100+ more expensive by the time I realized what had happened. But I was specifically advised that the $106 had nothing to do with a fare-increase per se.

I know that if a fare class sells out, a ticket re-issue into a more expensive fare class increases the price. In this case, the only thing increasing the price was the 20 minutes over the 4 hour "layover rule". This was confirmed by multiple agents/supervisors.

Since when is something over 4 hours a layover? And if there are only two flights offered, one that leaves an ~85% chance of missing a connection and one that arrives with a 4 hours and 20 minutes connection -- shouldn't that be the exact situation that a living, breathing, thinking Premier Line agent realizes is ripe for a policy waiver? This is not McDonald's where, if there is not a button on the register, you are SIL, or is it?