As blackstange pointed out, generally with a therapeutic phelbotobmy of 500ml of blood loss our HH will drop 2-3 points. Our HH has a variable rate of rise and fall throughout the day, for the most part this is relative to one's hydration status. Moments of hypoxia also come into play. Hypoxia can be formed from a few thing's that can result in low oxygen intake such as sleep apnea, severe sinus congestion, in which under a load demand situation where increased O2 is needed such as strenuous exercise or cardio. The congestion can lead to habitual mouth breathing, which can lower tissue oxygen. Therefore signalling to EPO→bone marrow to produce more RBC.
Are you at a critical level of your HH? No I don't believe so, yet that's not my decision to make. There should be a level of concern nevertheless that you don't have an underlying cause such as OSA.
Great reply Stewie! Thanks so much.