Why do transit midpoints keep changing by the day? Is this normal?

I was paying attention to to a midpoint yesterday Sun/Moon = 7 Ari 43 for the date 7th february. Today I noticed the degree has changed to 10 Ari 43. Is that how its supposed to be? I thought I was losing my mind but now I have caught it.

Hi. A transiting midpoint moves at the average speed of the two bodies concerned. Since the Sun moves at slightly over one degree per day, and the Moon moves at over 12 degrees per day, the Sun/Moon midpoint moves at around 7 degrees in any 12 hour period.

I'm not sure why you are tracking the transiting Sun/Moon midpoint, but its aspects your natal positions are unlikely to be noticeable.