brake pedals and ovaling of holes

[Nina Barton <ninab@scoresheet.com>]

Since my newly replaced master cylinder was leaky, I have removed it to
replace with a new unit.  I notice that the push rod and the brake pedal
are ever so slightly ovaled, which wasn't true when I replaced the unit 3
months ago.  Why does this happen, and what should I do to avoid it in the
future?  I did look in the List Quest archives, but was not real successful
in finding an answer.  Thanks in advance,  Nina