If your question is "why?", then note that Fortran specifies a maximum line length (if the line consists solely of characters of default kind): 72 for fixed-form source and 132 for free-form source. You don't say which you are using, or how the lines are indented, but the location of the "(1)" in the error message will give a good indication as to whether this is your problem.
gfortran will accept a compile-time option to change the line length limit, but for readability and portability it will be best to break the line within the default limit, using continuation.