Computer codes are not as simple and elegant as Pythagorean Theorem. They can involve hundreds of variables with thousands of if statements. Missing one if statement, or mistake a minus sign, and you walk on a completely different path.
Not saying this was a system glitch/error fix, but I think we should still keep this possibility as a contender.
Only thing I have to add is I can see scenarios where the formula is skewed inadvertently between getting pulled from the CRA and getting plugged into the FICO formula. The FICO formula itself will always return the same thing given the same data--but the data being fed to it is, I imagine, often not 100% complete. One missing bit of information might trigger a point drop or increase depending on who's running the score.
Rebucketing Update -
February--my EQ FICO score was 726. No negatives, but I had one credit line that was pretty much maxed out.
April 8--it had dropped to 699. The only difference in the 2 reports was that I had paid down a maxed out credit line a little bit (but was still about 60% utilization).
May 6--I finished paying down that credit line, my utilization is now 0%--and my EQ FICO has jumped up to 745.
So that's a relief!