Yes, once the grains are removed and you bottle/store it. I would say it's fine for up to several weeks. It might get more tart, it might get alot more fizzy....or could taste more 'flat'...depending on what you used, but it's safe if refrigerated.
I WOULD SUGGEST CAUTION when opening tightly sealed containers...you might get some super carbonation build up, depending on the sugar content of the particular brew when you put it up...
I once wore purple grape kefir after a few days refrigeration..hehe...so use caution!
Enjoy your trip!
OH, for storing the grains. Put them in a LARGE glass container, double or triple the sugar (use rapadura or succanant if you can) and add in extra water and leave them on the counter at room temp. To allow for 'gasses' cover with a cloth and secure with rubber band top, rather than an actual lid. This will keep them happily brewing for the week. Supposedly you can store this set up in the refrigerator, but I think they stay happiest at room temp.