1994 Honda Accord cam seal reported as leaking?

First, let me begin by saying that our car has always
performed beautifully, and we kept her in Pristine
condition, in mechainical and in appearance.
We have regular tunes and major work on schedule
and the routine maintenance before its due.
Oil, tires, filters, every 3,000 miles. We are very
religious in our car maintenance!! Its a great car and
we show our affection in doting on her.

She was stolen practically in front of us and found
two days later in front of a house. It was towed
to a local dealership who claims that the cam seal
is leaking into the plugs and that the plugs are fouled.
The claim that this is a pre existing condition- or
that is what they told to the insurance agent. I called both the agent and the dealership and their
stories are the same. That our car was leaking oil
from the cam seal into the plugs all along.
My question is: Is this even possible?? Shouldnt
we have noticed oil or some starting issues? or performance issues?

Isnt it more likely that the thieves over revved our
engine and forced the seal to give?

Our mechanic is a veteral Honda mechanic of 25 years and Im dumbfounded how he could miss
an oil leak and all the related things that must occur
for this situation to have happened as the dealership
claims.

Your professional input is needed.