Just echoing what the others have said:
JUL 12th 2011 will be recognised by both US and UK officials as July 12th 2011, so it won't be an issue.
However, if the date was written as 07/12/2011, that would be interpreted in the US as July 12th 2011, but in the UK as December 7th 2011 - which is where you might have had a problem had the date been written in number format only.