Heat rocks and hot spots

[Dirty]

I have a question...do ALL heat rocks develop those "hot spots" that can burn your animals? I have two heat rocks that I've had for years. I check them every once in a while to make sure that they're not too hot. Do I have to worry about them developing hot spots over time?

[tHeGiNo]

Definitely. I wouldn't use them, at all.

[Dirty]

Thanks. I'm going to get some heat tape ASAP