Of all the stuff worth cluttering your brain with, this would rank low on the list.

Of course it could happen anywhere, at any border--but in point of fact it seldom does. I've personally crossed many hundreds of borders on all continents and it's happened to me just once--back in the old days when I hitched up to Canada to visit my sister with 17 cents in my pocket, no valid ID, and a plan to camp out by the side of the road during mid-winter (ca. 1972).

More likely: you depart one country, but the next requires payment of bribes before entry, a proposition which you decline (while smiling, shaking hands, and generally pretending you've got all the time in the world to allow a graceful resolution). This happens quite a lot--it once happened to me while entering Guinea, in fact, but with a bit of patience the problem dissolved on its own. I met a rider who'd spent the night in no-man's land entering Honduras (I think it was) after refusing to pay a bribe, then got bitten by a scorpion in the morning but was STILL refused entry even to head for a hospital. It made a good story, and he's still out there traveling the world.

Prepare adequately and don't fret about minor issues...but always carry a bit of food and water, since issues which do arise often take time to resolve. Don't panic unless you see skeletons lining the roadway in no-man's land.

Mark