Wood has low tensile strength perpendicular to the fibers, and if you notch at the bottom at a support, this is the type of stress introduced at the end of the beam. There is a risk of cracking there. If, for example, you had notched at the top, it would not be as dangerous (not applicable here). You can calculate how much you can notch with or without reinforcement. The glulam handbook provides formulas, but I am unsure if the formulas can be directly used for construction timber, but the principle is the same. Consider specific precautions, notches in the beam end.
http://www.svensktlimtra.se/sv/limHTML/
