Quite possibly, there’s also the problem that if you try to make a non-startling non-controversial announcement to passengers it can come out all wrong when you try to translate it into pilot or techie speak.
Given the rotation at IAD it is perhaps possible the inbound crew had an minor engine issue (?software related) which was either written up on arrival (or transmitted to the company whilst in flight), and maintenance made the decision to do the fix, whatever it was, on the turn...now maybe that action could have been done a sector or two prior, who knows, but it is therefore quite possible the outbound (IAD-LHR) crew for the 292 arrived at the aircraft to find a decision had been made and there was already work in progress, so had to pick up the delay and make soothing announcements.
More likely that happening than the outbound crew simply arriving at the airport and then opting for an optional upgrade.