That is not normal in the sense that everything is okay. It happens quite often but is usually related to some injury from borers, stress cracks in the bark or a canker disease. If the problem is scattered I would not worry about it. If on the other hand it is extensive throughout the plant then the plant's health is in jeopardy. There is little that you can do for such problems except in the case of borers where preventative sprays can help keep a problem from getting worse and if the initial damage is not too severe the tree may recover.
You might want to take a photo of the plant and another of the sap areas to your County Extension Office for the Horticulturist to look over and analyze. There is no charge for that service.
1982 Lytle Way
Abilene, TX 79602
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