It happen to me too, he just can't see what behind it, so he needs to crush it.
I get used to it now.
Same as the bot will stop reading books first at any book rack then continue the journey, no matter how dangerous the situation is.
Same as if the bot missed a small spot, it will run all the way back to that spot, no matter how far just to see what in that position.
Or when the bot see some place within his sight, but no way he could cross it without having to go all the way around. He just stood there waiting for "invisible bridge to appear"