It might be an indication of borers. However, I have a Rainier cherry tree that has been oozing large gobs of sap for at least 10 years or more ... ever since I've had it. The tree grew from a seed planted by some bird or squirrel. It produces bushels of lovely cherries every year.
I have no plans to "treat" my tree in any way. You, on the other hand, might prefer to go to some lengths to investigate the cause of the oozing sap on your trees. I'm just saying that it hasn't seemed to harm my tree in all these years, nor has it interfered with fruit production.
I found the following article on the subject to be of some interest. Perhaps you will, also.
"Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too?" - Douglas Adams