I always soak liquid into Sweet Tarts and let dry...One drop per tart. They are perfect -- much less suspicious than sugar cubes, they have a concave end, and if you do it right, you can slip them back into the roll so it doesn't even look like they've been removed (therefore no foil required).
To the OP -- if the bottlecaps were JUST LAID then the liquid might have dripped off. But if it had 1-2 hours to soak in (but was still a little wet), I'm pretty sure you're okay. Were the bottlecaps (the part with the liquid) touching anything, like other bottlecaps or foil? Do bottlecaps have a "coating" on the outside, like to make it smooth/polished? If so, I would recommend what the poster said below.
make sure when using sweet tarts or whatever candy to scratch with a quarter and then drop
Completely unnecessary with sweet tarts at least...Sweet Tarts don't have a "coating", they are absorbent on the outside. I have successfully done this 1000s of times. I am talking specifically about the sweet tarts that come in rolls, not the smaller ones that come in boxes that do not have the concave end.
Spree or Shock Tarts (which come in a roll like sweet tarts and are also produced by Wonka), for example, have a coating and I would never attempt to drop on there...