I recently had some funny business on a United Airlines flight where the high-low chime (you hear for the seatbelt sign and landing gear, etc.) was going bonker

I recently had some funny business on a United Airlines flight where the high-low chime (you hear for the seatbelt sign and landing gear, etc.) was going bonkers and chimed maybe 10 times in a row while the cabin lights faded on and off. No announcements were made by the pilot or flight attendants afterwards, and everyone was left confused. I turned to the passenger next to me and we both shrugged.