Those aren't eyelashes. They are the blobs caused by bobbin backlash. You will notice the majority of them seemed to happen when you are coming to a sharp point and abruptly change directions. Bobbin backlash happens when you change speeds abruptly, like coming to stop then switching directions. Especially when going fairly fast before doing it. It is caused because your bobbin is spinning inside the bobbin case and continues to spin even when the machine is stopped. This results in the excess thread being available in the hook and getting these loops on the back. Bobbin backlash is characterized by a large loop of bobbin thread happening in odd places.
I can't stress enough that this is NOT a tension issue. Especially when you say that it only happens sporadically and the rest of your stitches look good.
Do you have an anti backlash check spring for your bobbin case? Those help alleviate the problem but unless you slow down and are aware when you change directions, it can still happen. Magic Genie bobbin washers also help to alleviate it.
The only product I have ever found that eliminates them completely, aside from being hyper aware of abrupt changes in speed when you are moving the machine head, are magna glide bobbins. The bobbin core has a magnet that stops the bobbin from freely spinning inside the bobbin case.