I replaced an older GFCI outlet in a bathroom with a new Leviton model. I followed all instructions. When finished, I pressed the Test button it shut off itself and the other 3 downstream receptacles. Pressing Reset resumed function. However, soon after I noticed an unusual, acrid electrical burning plastic (phenolic resin?) smell coming from the GFCI receptacle itself. I had to get within a few inches to be able smell it. It was also a bit warm to the touch. There was no heat damage to the wiring inside the box. So I removed and disassembled that GFCI before discarding it, just to see if there was any signs of overheating, discoloration, or arcing inside the contacts or the internal circuitry. As best as I looked, I could see none...it looked completely new inside. But that smell seemed (but not 100% sure) to be coming from the internal circuit board itself. I discarded that GFCI.
So I temporarily replaced it with a new non-GFCI receptacle. It worked fine, no unusual smells or warmth whatsoever. So today I removed it and re-installed a new GFCI - same type/model as the discarded one that was giving me the unusual symptoms before (it is from the same 3-pack). I installed it the same way, again following the instructions and checked by pressing Test and Reset - and it shut off and resumed as it should. I also had a night light plugged into this GFCI receptacle while I pressed Test and it shut off as it should, and resumed when I pressed Reset. Also my plug-in circuit tester says it's wired correctly...top and bottom halves of the receptacle. This new GFCI has a very similar (phenolic?) 'circuit board smell' as the previous one, but much less/milder of a burning smell...and only when I put my nose to it. And unlike the last one, I feel no warmth from touching this GFCI.
I was told that pressing Test and Reset several times within a span of a few minutes (as I did with both newly-installed GFCIs) should not cause any problems. Is the smell I describe normal for a new GFCI? I expect electronic devices to off-gas a bit when new and powered up/warmed up for the first time, but this (especially the first one) is/was worrysome. Thanks.