I don't see anything to worry about.

Broken pipe is the message you get from EPIPE which is the error you get if a write is attempted on a pipe where the read end is closed.

As your pager is the read end and is quitting, it's closing the read end of the pipe. Hence the program writing to the pipe, man in this case, is going get an error when it tries to write to the pipe.

So the error message is coming from man, not pg.