Do iOS apps crash regularly? Is this normal? I've been having some trouble with one of the third-party apps on my iPod Touch 4gen, and realized that a lot of apps I use (which isn't many) have been spontaneously exiting, recently.  Safari and Youtube both did this a few times today.

Is this normal?  iOS apps tend to go back to what they were doing, so it's not that big a deal, but perhaps it's indicative of some hardware or software issue.

I'm using iOS 4.2.1.  I don't remember it being quite this bad on 4.1, but that could well just be my imagination.

I looked for crash logs on my computer, but there's been no crash logs created in over a week, even for apps which I know have crashed many times since then.  I don't know what that means, if anything.

Should I be concerned?  Is there anything I can do?  Is there some kind of "is my iPod completely &amp;#@!ed?" diagnostic I should run?  I realize this is kind of a vague question.
It could be a low memory issue. iOS is supposed to manage memory automatically, but I've found that it's not always perfect. Try quitting every single app and restart the device (hold the power button down for several seconds, then slide to power off, then power on again) to see if that fixes it.