Greeting from a little further north in New Jersey!
I had a situation like this occur last year. I hired a friend part time to help them out through their recent loss of a job.
Long story short, I landed a large window cleaning job on a college campus in Central NJ. I was paying my friend $20 an hour for the help.
When that friend realized how much that job was going to cost, they DEMANDED $300 for the day, or they wouldn't work.
... and that friend hasn't worked for me since.
I'm a firm believer of giving a little extra to my employees every once in a while for a good job done. However, if they ask for it, or demand it, I consider it an insult and feel they're trying to look a gift horse in the mouth. Thats totally not cool.
I wouldnt give them the extra now, simply because they asked for it. I would however give them a few extra dollars, a tip if you will, in a few weeks just to let them know that their hard work is appreciated.
Good luck with that!