Just because the pipes get hot it doesn't mean heat is being wasted (if that's what you thought). Hot water bypassed back to the boiler raises the return and flow temperature causing the gas to throttle down (modulating gas valve) or go On/Off (non-modulating). If everything is working OK I wouldn't worry about it.
While working in the airing cupboard today I notice the pump runs on for a while once the boiler is commanded off and the abv does something useful at this point.
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