Sometimes, when my toilet is flushed in the middle of the night, it will make a high pitched whining noise for several (5-10 seconds) while refilling. This doesn't happen during the day, and it only occurs sporadically in the middle of the night.
Can this be caused by higher water pressure during the middle of the night?
Could the temperature of the water be the culprit? It is mid-April right now, and the daily temps are just starting to get higher (like in the 70s).
I have attempted searches on the internet, and most point to the refill valve or ballcock assembly having issues, but since this only happens sporadically, and in the middle of the night, I am wondering if it could be some cause outside of the toilet.