Good App But Eraser Acts Weird

I really like this app -- great for drawing and doodling, like all the brushes, color selection, etc. But the one issue Im having (and I saw another reviewer mention this same thing) is that sometimes when you use the eraser, instead of erasing, it leaves little ) marks everywhere. At first I thought this was some special effect or something but I cant find a way to make it stop other than shutting down the app and reloading!

akanuk about Tayasui Sketches