Did you have a different number of accounts reporting balances? You could have a total of $100 reporting, and it could be on one account or spread across 5 accounts. That's an easy change to overlook.
Take a look at screen two of your recent reports and look at the negatives that are listed. Did they change in order? Did a new one appear, or an old one disappear? The negatives are the factors that effect your scores, with the factor with the most impact listed first. btw, the positives are pretty much warm fuzzies. I think that they're the negative factors least effecting your scores, from the bottom of the list in other words.
For the new member who posted above, job status and income and savings and all the rest have NO effect on your FICO scores. They're not on your credit reports. Scores are generated off the info on your reports, so if income, etc isn't listed, it isn't scored. Simple as that. Welcome to the forums, btw! 
eta: whether a HELOC is factored into scoring depends on its CL, not on the balance. So paying down (or borrowing more) on a HELOC shouldn't make it pop on and off your util. But if the lender mis-coded it one month and reported it incorrectly somehow, that might have done it.
The TU sim includes higher-CL HELOC's, lines of credit, and CC's in the revolving util, but that's just the sim. It's not in the real score. I have a HELOC that is generally anywhere between 50% - 80% util, but its changes are never reflected in my TU FICO.
