I noticed this as well (even signed up just to write it).
Will try to re-create it. I had the glove with a HV battery, railgun and was hit (or close to at least) by a Ghast.
Other modules: Jetpack and shock absorber.
Heat went through the roof and did not appear to go down. I'll see if I can recreate on my server.
OK done. Heat does not dissipate in nether for me. Modules installed: Jetpack, shock absorber, heat plating on all armour parts (set to ~1kg weight), railgun and HV battery on glove and one other part.
First time it happened suit was crafted in 1.1.6, second time in 1.1.7.