The water heater does not have an ‘overflow valve’, that is a safety temperature and pressure (T&P) relief valve.
You can first try changing the T&P valve. This may relieve your condition. However, this may possibly have little or no effect.
If this does not have much effect, the problem may be that you need an expansion tank installed.
If the temperature of your incoming water is much colder now (what is the cold water like at your cold water faucets?), then your hot water system is being subjected to expansion greater than what occurs in warmer weather when the cold water supply temperature is higher.
Water being heated from 70° F to 120° F does not expand as much as water being heated from 50° F to 120° F does.
Thus the problems due to expansion are just now starting to show themselves.
Another question: Why was the water on the laundry room floor? This relief valve’s discharge line should not be draining open to the floor where water can collect and cause standing water. Does the end of the discharge line just end above the floor?