iPhone 4S-Diedlocked up twice in month

Greetings!

I have had my iPhone 4S for a month now, and unfortunately I have experienced some issues with it already. Twice the telephone has stopped responding to sleep/home button input and the screen went black, in addition it didnt register the power adapter nor register with iTunes in this state. Seems like it has went into a loop of sorts, as it responds to buttons when it is completely drained of battery (hours later). I recently found out that pressing and holding home + sleep for 10-20 seconds forces a restart on the telephone. I haven't experienced this again in order to try it yet, I wonder if the life of the battery can be saved this way. It is only a hotfix to the problem, or as they say "curing the symptomes" and not the problem it self.

I guess my question is this:

Is it a hardware or a software error? If it is a hardware problem I'd like to get a new and reliable iPhone asap.

If it is definately a software problem that will be remedied in the next few iOS patches I am willing to wait it out.

Don't want to send in my telephone and receive one that has the same problem, so I ask you here.

Thanks for any light you may shed on this issue,

Jon