I have a pug, and she constantly has "eye goobers", that's just her breed. But it could very well be from the smoke and crud in the air. I would say as long as their eyes don't look sore, or the stuff isn't a funky color, it's probably just an allergy or something of the sort. Like others said, damp cloth to wipe it away and maybe just keep an eye out to make sure it doesn't get infected or anything