I'm sure you're fine. That finger of foam was likely your fermentation. Usually, I expect to see activity start between 10-30 hours after pitching yeast. If I don't see anything after 36, I worry. Usually, things are done visibly four or five days after seeing activity start. Sometimes quicker.
Caveats: if your temp is warm, things can happen faster. If you're doing a big beer, things can take longer. Even if the visible part is done, your yeast is still doing important things, so let it be after the foamy bubbling stops.
If you sanitize something to take a small sample, taste it. It should be pretty obvious... fermented beer will taste like warm, flat beer. Unfermented wort will taste like sickly sweet syrup. Again, I think you probably are fine. Lids are famous for not sealing. Even if the lid isn't cross threaded, air can escape easily. No big deal, just makes brewers nervous.