I've managed to take some pictures of the problem...
http://flic.kr/p/d8y3xL here small round tiny spots can be seen in between two frames
http://flic.kr/p/d8y3dh here basically the same tiny round spots (etched in the emulsion) can be seen emulsion side after the negative was rewashed in Tetenal Mirasol Antistatic 1:400
http://flic.kr/p/d8y34C same as above
http://flic.kr/p/d8y2Wm same as above
http://flic.kr/p/d8y2Kq same as above
http://flic.kr/p/d8y3pY same as above