Absolutely no problem.
I would take that with a grain of salt though.
If you computer seems to get extraordinarily hot and sluggish, or even lock up after a few hours or even a day, there is defiantly something wrong with the hardware and you need to get someone to look at it.
If you suspect that you have a heating issue with your computer, I would go to http://www.almico.com/ and download speedfan, which is a free program, and log your results.
But simply put, 30 hours is not an issue, in fact 30 days or 30 weeks is not really an issue if the computer's health is fine.
Think of it this way, if your Internet provider has to keep their computers running for months on end to provide you and all their customers constant Internet access under a constant CPU strain, do you think you are really going to have a problem with your computer then?