Low battery warning in front of message, cannot close

Hi,

Using iPhone 4S (still) it seems to work so that's good 🙂 (just a bit slow though).
Anyway, I message a lot (as does everyone) and received that message on top of the message I was reading (I don't know what you call that? When you can reply to someone else in a tiny popup message window comes on?)

I began writing my reply (in that popup message thingy that's part of iOS) then all of a sudden received: Low battery warning.
BUT, since I was replying inside that tiny message at the time, the OK box for low battery was hidden from view!
I could not type anymore letters OR even press Send on the message!Since I had no OK button, nor could continue writing my reply!

I found the ONLY way to get my iPhone back to normal (usable) was to press the top button to blank the screen (as not even the Home button did anything!)Once finding the message (that popup message) person again, my entire reply message was gone. I then needed to start the reply again.

I'm not sure if this is a known bug? But it obviously should be.
Obviously I have the latest iOS and nothing else was open (except obviously my messages on the phone itself).

Is all this clear? I feel like I rambled on a bit 😀

Thanks for any replies (or views from others who may have seen this issue/bug).

Oh and I created my Username as kimsland about 3 years ago, but now it says this name is already taken? So I ended up putting a number in my name. I wouldn't mind my original username back 🙂