Avocado grafting white powder?

I just grafted a bunch of bark and veneer and t bud grafts and on some, there is white powder around the graft connection. The white powder is dried sap. However white powder is also a sign of canker?

Is this normal when making incisions and grafting or is this a canker problem that needs to be cut out as described here:
http://ipm.ucanr.edu/PMG/r8100611.html

Thanks!