Yes, it is the first symptom/warning of a shorted out battery.
This happen to me with two of the four 6 VDC batteries I had in my battery bank. There were all of the same vintage too.
I do not know what would cause this to happen, but I noticed mine over a 2-3 month period. Normally, I would only put a little water in every few months or so. Whereas I was now putting a pint of more in every two weeks.
The last straw was one day I opened the battery compartment door and the smell of battery gas was over powering plus two batteries were very warm and the outside casing was bulging. That's was enough for me to disconnect them immediately BEFORE they blew up.
I removed all four and replaced with new ones. That resolved my problem.
I also use Water Miser caps which reduces the frequency of having to add distilled water to the batteries. Now, with the new set of 6 VDC batteries, I only add a small amount every 4-6 months or so.
Dr4Film ----- Richard
2002 Monaco Windsor PBT 40Ft. (R HOME) - 30Ft. 2006 Pace Trailer (R JUNK). Trailer Has 06 VUE (R TOWD) 04 Victory Alen Ness Edition (R RYDE). Full-Timer for 14 Yr's BUT now a Part-Timer. Cummins ISC-350 With Banks Power Pack and Upgraded PRXB PacBrake.
Winter Home in Flagler Beach FL - Now Staying in Dansville NY for the Summer.