Humidity sensor paid for itself after one mold scare inside my garage

Last month I pulled the tarp off my '72 Cutlass that I keep stored in a rental unit over near Springfield and the seats smelled like a basement. No visible mold yet but that musty hit makes your stomach drop. I checked the cheap digital hygrometer I had sitting on a shelf near the door and it was reading 78 percent. That thing said 60 percent back in March when I put the car away. Either it was lying or the weather did a number on the unit. I dropped $35 on a proper sensor with a remote app and now I check it from my phone every morning. Has anyone else dealt with humidity creep in a storage space that seemed fine for like 3 years then suddenly got bad?