this is completely normal behaviour, as on a desktop. I'm not sure about the US keyboard layout though, but usually, "^" is an accent applied to other letters, e.g:

1) You press ^ once - it doesn't appear.
2) You press a - what appears is â (same with êîôû)

This is the same with ` and ´ and ¨ to get the letters àèìòù and áéíóú and äëïöü

You can also simply press the symbol twice, to get the same effect. E.g. I press ^ four times to get ^^

As I said I'm unsure if this should also be the case with the US layout. If it's not like this on a US layout desktop, it might be a bug to be reported, but for all non-US layouts I know, it is normal that the key does not appear after just one touch.

^^ !