There are a few of them that are fairly standard/understood to be part of the repertoire, whether or not they are written in the score/parts. For the life of me none of them are coming to mind. Depending on the work it might actually be indicated, or there may be a fermata over a rest at the end of the bar, over an empty bar etc. that serves a similar purpose. If they aren't in the part but typically happen in that work then writing them in is a good idea and helps the next guy that gets the part.
Once in a while a conductor will add one that "shouldn't be there". This could be for something utilitarian such as facilitating a page turn for a particular section, or usually to add drama. I have encountered some that were really effective, some that were entirely tasteless, and quite a lot in between. It can be equally as (non)effective to play through an expected pause or play movements attacca (immediately after one another without a break) with most of these being written or understood as standard, with the odd conductor whim thrown in.
If you encountered it last night for the first time hopefully in a rehearsal, I would advise paying particular attention to that spot during the performance. While conductors are known to take liberties and do things in concert they haven't done before in rehearsals, these can go from a brief pause to an all expenses paid vacation in the middle of the piece, or they can fly by in a fraction of the rehearsed time. Keep your head up.
