Lantus often has a "double dip" where the PMPS is lower than the numbers late in the cycle, but higher than the nadir. I think it's totally possible that she went lower today sometime between +2 and +8
Also, when their pancreas is sputtering back to life, giving a little food can trigger it to start "kicking in", so you'll see a lower number a few hours later.
When on an OTJ trial, we'll tell people that if they get a higher Pre-shot number, to try feeding and recheck 2-3 hours later...if the number comes down, that's a sign that the pancreas is working