For the purposes of this thread, I am going to assume that you, as you say, smoking slowly, drying your tobacco, etc. I believe you when you say it, and more importantly, it allows me to dispense with the obvious.
Let me ask a few questions, and let's see if we can pin this down.
1. What is the climate like where you are smoking? If you're smoking outdoors and it is humid and hot outside, or if there is a fairly decent breeze going on, those things can make your pipe burn hotter than normal.
2. Is your bowl hot all over, or do you find the heat is concentrated in one section in particular?
3. What tobacco(s) are you smoking? Some will smoke hotter than others and require a bit more care when smoking.
4. When you draw from your pipe, does it feel smooth? Or do you feel you have to draw harder than normal? If the latter, you may have an obstruction near your draft hole. There are many ways to deal with this, but a pipe cleaner can do the trick easily enough on a straight. For pipes with a bent, you may have to remove the stem. A lot of folks feel as if this is a big no-no, so if you feel that way, maybe let your pipe cool before removing the stem.
5. Finally, the way you pack and what you choose to light with in the first place all have a big impact. The former is something you get a handle of with practice, so I'm not going to be much help to you there. But the latter I can. If you're lighting with a bic torch or something similar, consider something that provides a softer flame, like sulphur-free matches. And when you relight, try to draw the flame to the tobacco as close to the tobacco without it actually touching. If your initial/false light was done well and tamped appropriately, you can usually get your pipe going without the flame from the relight actually contacting the tobacco, or if it does, only briefly. If during relights you are scorching your tobacco, then it will burn hot, cadence be damned.
