mysqld process deleted in lsof

running lsof on the server today I came across that mysqld was showing up as deleted. Does anyone came across something like this before, or there is an explanation about this. Is it a bug?

lsof | grep /usr/sbin/mysqld
mysqld     2589     mysql  txt       REG              253,1   12681241     312101 /usr/sbin/mysqld (deleted)

Verify that in fact the mysqld binary is present on the filesystem:

ls -la /usr/sbin/mysqld

If it is there you probably upgraded mysql but did not restarted the daemon, hence the binary in memory was deleted and is now different from the one on the filesystem.