This for loop is fine as it is, but will generate warnings if replaced with a parfor loop.

See the other messages that accompany this one. Note that these other messages do not necessarily indicate a problem in your current code, but rather problems that you will see if you convert the for loops to parfor loops. By default, this message is off. You can turn it on when you are considering converting some or all of the for loops in a file to parfor loops. When the conversion is complete, you should disable this message again until needed.