Maybe the crew was aware of the previous 'well known to some people' BAC 1-11 inflight flight deck window failure and what effect it had on that aircraft's crew and the safety of that flight!
This being Flight BA 5390 from Birmingham, England on Sunday, 10 June, 1990 en route to Malaga, Spain. If it works, the following link descibes what happened: -
BBC - h2g2 - Oh, What a Flight! - the Story of BA 5390
Given that knowledge, perhaps they thought it wise to get the concern further investigated by an Engineer rather than 'assume' that all would be fine for the rest of the flight. Maybe the crew was aware of some recent window related maintenance having been carried out or some other factors that may have given them particular cause for concern during their flight? I do not know the facts surrounding this event but I doubt that their decision would have been taken lightly.