While the there's only one line there, it'll be a nuisance, and you can't be sure that more lines won't develop. It's worth while to take advantage of the offer to repair/exchange.

enTourage itself is superb for dealing with warranty issues, so have no fear at that front. I doubt they have a European repair depot - you'd have to ask them. If they're asking you to send it to the US, it suggests they don't.

To prevent damage in transit, be sure to wrap your eDGe in about 1" thickness of bubblewrap, or surround it with a couple of inches of "popcorn" packing material, otherwise, with several inches of crumpled up newspaper. It wouldn't hurt to slip your eDGe into a plastic bag before packing it.