it's not great, but it won't hurt it.
it got less energy that day... a very cloudy day might be similar.
it depends on region too... the sun is much stronger in some regions... you can reference a regional DLI may for the time of year -- any good source will have 12 months of maps for your area as it changes with seasons too... the world revolves on a tilted axis relative to the sun.
if in a high dli area, it may have gotten a good amount even with 8 hours, but most likely was a bit short that day.