Water dripping from heater pressure relief valve

No problem at all. it will "gradually" get worse, but there is NO hurry to change it. Also, it is a common item available at any hardware store, NOT RV specific. Just pull it so you know which model you have, there are 3 or 4 different ones and go to your local store to get a replacement. I was in the same boat and went a year before I changed mine.