Happens to me quite often too, usually when I'm tired or under physical or psychological stress. That could be it. Fun as most holidays are, travelling still tends to put a fair degree of stress on your body, especially if you are going through different timezones.
For me, the spasms go away after a good night's sleep. No worries.
You'll be fine dude. [img]graemlins/thumbsup.gif[/img]