I wouldn’t worry about slight changes in either direction. 
It’s not necessarily a bad thing.
Here’s a post from @xertedbrain from a while back –
HIE is … a number that represents the shape of [the power] curve with larger HIE values meaning the curve is wider to the right. Smaller HIE values make it more narrower.
HIE … is conceptually in line with burning carbs. A bigger HIE allows you to hold higher intensity longer and this essentially means you’re better at burning carbs. Burning carbs faster is equivalent to able to produce more power . They are synonymous. So while having a bigger HIE might mean ability to ride higher intensity for longer durations, it also means that you’re burning up carbs more too. This isn’t ideal for longer races or ultra-distance events. Hence having a smaller HIE in favour of a higher TP is better, even if that means lesser power at shorter durations. This is captured in LTP which is inversely proportional to HIE.
Related posts –
What kinds of workouts improve HIE? - Support - Xert Community Forum (xertonline.com)
PP, HIE and TP relationships - General - Xert Community Forum (xertonline.com)