I don't see how. There are two reactions that can remove some OH- from the solution containing Ca2+ and OH-. One is production of CaOH+, the other precipitation of Ca(OH)2. In the solution you described there is no way to see precipitate (we are below solubility product), and CaOH+ is present only in a minute quantities (8*10-5M) - that means pH can be lowered by about 0.1 pH unit, to 10.9.
I suspect some problems with the pH measurement.