Wondering if I'm having an iPhone problem

I just switched from a 3GS to a used 4, and I'm not sure if I'm having a hardware issue or just a lesser antenna issue.

I usually listen to a streaming radio app while I'm at work with the phone in my pocket. Mostly TuneIn, IHeartRadio or Radio.com.

When I had the 3GS, it would play for hours and never seemed to stop or buffer. It does with the 4. Not constantly, but maybe once every hour or two.

Is this normal or does my phone have an issue?

Thanks for reading.

It could be (I'm just idly speculating here) that something in your pocket is diffusing the effecitveness of the iPhone 4's antenna. Anything else metal in there?

This might be the app.
Like on Pandora.com when you listen to it for a certain amount of time, it will stop, and make sure that you are listening to the radio. But when I am on my iPhone on the Pandora app, it does not stop, which is why I like Pandora on my iPhone better then the website.

When you turn on your iPhone when it stops, does the app like time out?

Thanks for the replies.

I'm thinking perhaps it's just the iPhone 4 just has a bit lesser antenna. Especially at my location at work. I don't have anything else in my pocket sans iPhone. If I listen in the car it's fine also, so perhaps in my pocket the signal gets ever so slightly diffused.

It isn't an issue of listening too long because sometimes it will stop just a few minutes after I start listening. I did set the TuneIn buffer to it's highest setting, 30 seconds, and that seems to have helped a bit as it just cut out once yesterday during about 3 hours of listening.