The seal may be there, you just don't see it. Not trying to insult anyone here.
Long story short, I think I FUBAR'ed my SIM card slot because I had to use a nano->microSIM adaptor, when I was removing my sim card, half way out, something "snagged" the adapter, I couldn't get my SIM out so I pulled/forced it out. When I tried reinserting the SIM card, the "spring" doesn't work and my card was stuck inside...furthermore, no SIM detected so there goes that idea.
I removed the back panel and battery to get to the SIM card slot from the inside. Following Kurt's maintenance video, I removed the 2 additional screws inside to remove the "interior" cover. ONLY then did I notice the thin rubber seal around the edges.
TL;DR - maybe it's just me but I didn't notice the thin rubber seal until I further disassembled the TS.
Motorola Moto X (XT1053) - [KK 4.4.4] Krypton v1.4
Asus Google Nexus 7 (1st gen) - [KK 4.4.4] ♦ PURITY ROM
HTC One XL
-> HTC Inspire 4g/DesireHD
-> HTC Hero GSM
-> HTC 8525/TyTN
-> Motorola Q9h
-> Audiovox SMT 5600
-> Nokia 3650
-> Samsung SPH-A460
-> LG SP510
Sorry HTC, you have disappointed me for the last time.