Why might the O—H stretch in the IR of MY triphenylmethanol product be less intense than expected?
A possible explanation would be the concentration of sample you used. Of course, if you are confident that you had utilized sufficient concentration then there may be another reason for the decreased intensity. However, some of the other peaks are also somewhat decreased in intensity so it is a possibility. 

This point is noted here (http://chemwiki.ucdavis.edu/Physical_Chemistry/Spectroscopy/Vibrational_Spectroscopy/Infrared_Spectroscopy/Infrared%3A_Interpretation#The_Origin_of_Peak_Intensities)