If the car has stood for a long time, it may be a bit of rust on a valve seat or bore, could be a ring a bit gummed up etc.
The results don't indicate a 'failure' at this stage, but keep a check on compressions every so often, and don't try winding the boost up to 'pushing your luck' levels.
May be worth checking crank endfloat if you notice something different going round a corner. One of the classics is chuck it round a right hand bend then declutch and see if the bite point is lower letting it back up.
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If at first you don't suck seed, try drier grain.