Motor Blows smoke on decel????

just what the title says, after 11 years of hammering the poop outta my 340, tonite i looked out the back window after i pulled her up to 5500 rpm or so in drive, and saw blueish white smoke out the tail pipes when the engine came down to about 3800rpm after letting off the throttle and coasting down.
Is this worn rings? it doesnt smoke in the driveway if i rev it up, nor does it smoke under "normal" driving conditions, if i bring the revs up, and let it decel while gradually backing off the throttle i get no visible smoke !

im really hoping its a tuning issue.....

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after 11 years of hammering the poop outta my 340, and saw blueish white smoke
im really hoping its a tuning issue.

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I hate 2 b the bearer of bad news. I'd start w the basics: leakdown/compression. Might b a borderline intake side gasket leaking under the high vac conditions or just (hopefully) valve stem seal(s)