I believe (but I am not certain) that Bentsen later expressed some misgivings for being on the ticket with Dukakis.
Goodness...who wouldn't?
After getting trounced and embarrassed by the guy's campaign skills (tank helmet thing), I would be angry at Dukakis for destroying and trashing the balance of my political life too!
I'd want a source before I believe that one, and "some misgivings" are pretty far short of repentance.