iPhone Bug and/or Virus

OK, this is on a 3GS that isn't, and has never been, jailbroken.

Firstly, I came across one potential bug this past couple of weeks where Safari, would act all screwy and the only way to fix was a reboot. The symptom is that I tap the bookmarks button in Safari, and the bookmarks screen pops up. However, the bookmarks button remains highlighted (lit up, like when you tap it), and everything is unresponsive. I can go back to the springboard by pressing home, but Safari has ceased to function, even after clearing out the cache, history etc. Rebooting the phone fixes it. This has happened 3 or 4 times in the past 2 weeks, never happened before that (nothing has changed in this period, I've been running v3.1.2 since it came out. Doesn't happen all the time, mostly Safari functions without any issues. Has anyone else come across this?

The other issue is very very odd. I was posting a PM in another forum, and I tapped and held the screen in some of the text I had typed (as one does to position the "cursor", when editing text), and when I removed my finger from the screen, the text "AVirus" had appeared in the middle of the word where I had selected. I know, very strange indeed. I might understand this more if the phone was jailbroken, and it was actually related to one of the recently discovered iPhone viruses, but it's not jailbroken and never has been. I've not been able to replicate it and unfortunately I didn't think to take a screenshot at the time, but that's what happened. And I had definitely not accidentally copied and pasted this text from somewhere else. I confirmed this by immediately pasting whatever was in the clipboard, and it wasn't this.

I am hoping this was just some very random bug in the OS or Safari. But I'm going to do a full restore on my iPhone tonight, just in case it's something more sinister.

Has anyone else ever heard of anything like this? I searched the forums, and googled it, but came up with nothing.