Anyone have any experience with leaking push rod tube seals?

Actually, EVERYONE has experience with leaking push rod tube seals.
Not everyone realizes it, though.

Seriously - as long as it's not leaking much and you can be confident
the oil is actually coming from there, it's not a big deal. On
Lycomings, the pushrods are on top so there's no way to mistake a leaky
pushrod seal for anything else. It's not really that they leak any
less than the Continentals, it's that the leaks are generally ignored
since they have no real safety consequences. On a Continental, it's on
bottom. The advantage is that the camshaft gets properly lubricated
(unlike a Lyc) but the disadvantage is that the pushrod tubes are a
pain to get to, and it's very easy to confuse a relatively benign leak
(pushrod tube seals) with a nasty one (leakage at the base of the jug,
for example). Since you don't want to mask a dangerous leak, you need
to fix the trivial one.

If it's really the pushrod tube seal that is leaking, it's not a
cylinder or a case issue - it's either a bent/cracked/otherwise damaged
lip on the pushrod tube (usually damaged during assembly) or a damaged
seal (also usually damaged during assembly). The oil there is not
under pressure, so there should not be much of it leaking. It's a very
minor problem in terms of parts and labor, and really you could fix the
problem yourself in 30 minutes by straightening/smoothing the pushrod
tube (if necessary) and replacing the seal (which I think costs about
$3).

Michael