The Northern Irish 'wee'

In Tescos everytime I go through the checkout "would you like a wee bag"?  Not necessarily a small bag but definitely not one that you'd wee in.

My northern Irish mate uses wee the same as Scots do. But then he did live in Scotland for a few years....

I recently spent some time in the company of some people from Northern Ireland and was confused that they'd say "whenever" in places that I'd have just said "when". Of course I can't bring a good example to mind right now, but it was sort of jarring to hear.

Or is it just me ?

My Northern Irish friends use it the same as Scottish do.