Sometimes you think it’s stuck, but you find the string later wrapped around your thigh. Or worse, you realize you never actually put one in, and your panicked fingers were just searching for a phantom. Cue the awkward giggle.
Rule of thumb: if you’re not sure, check. Use a clean finger and a fresh pair of eyes (or a hand mirror). If you see nothing, and you feel nothing, congratulations—you’re just forgetful. Put a new one in and move on with your day.