While the distributor is driven by the cam, the ignition timing is set to the crank position, and controlled by the ECU. I think there's a "procedure" for setting the initial timing at or near TDC, and then letting the ECU do it's thing, but I'm not familiar with the specifics.
I don't think 135k is so many miles that you have to worry...yet. If it had "jumped a link" your valve timing would be off, but this is highly unlikely.
Your ECU may be the culprit.
cm
