Could be a small krausen?
I would give it a good whiff and pour a bit off to taste. It'll taste like rear end, but it should taste like a yeast's rear end. If it doesn't smell like yeast and doesn't taste yeasty or has more of a 'bite' to it, then toss it, chill your wort as cold as you can and if you've got a fridge for fermentation, get it colder in there, and run out and grab a new vial and pitch it, if your sanitation is good, it should be fine till tomorrow. I would hate to see your Saison turn into a bad rendition of a lambic.
My experience is that if it doesn't look like foamy krausen but more of a silky set of bubbles or skin, it's bacteria.