plimit vs ulimit

Would anyone be able to explain why these two queries regarding file descriptor limits do not agree?

1. (check tomcat user's open file limit, soft and hard)

# su tomcat -c "ulimit -Sn; ulimit -Hn"

256

65536

...which is the typical default

2. (run plimit against running tomcat process)

# plimit 2359

2359:   /tools/jdk1.7.0_91/bin/sparcv9/java -Djava.util.logging.config.file=/t

   resource              current         maximum

  time(seconds)         unlimited       unlimited

  file(blocks)          unlimited       unlimited

  data(kbytes)          unlimited       unlimited

  stack(kbytes)         8192            unlimited

  coredump(blocks)      unlimited       unlimited

  nofiles(descriptors)  65536           65536

  vmemory(kbytes)       unlimited       unlimited

Would the soft/current limit be higher for the process because something in tomcat has explicitly increased it?  I have not done this in any start script so I don't know why else the limit would be so much higher for the running process vs what ulimit reports.