Sander’s taboo dropped for me in norm act 2 tals tomb. I did not know this could drop in Tals tomb on norm because the monster level there is 17 and these gloves have a level requirement of 28. Is this odd?
I think that seams normal. Tal Rashas tomb is a great place to look for loot.
I just thought item levels are suppose to be equal or less than the monster’s level.
I am unsure of that. I don’t know much about the numbers. I’m pretty sure I found sanders gloves in normal myself. I know I have a pair.
duriel dropped gloves and boots for quest drop on one of my chars in normal.
totally normal to see.
The gloves require level 28 but their item level is 20. Unique monsters are monster level +3, which would make Unique monsters in Normal Tal Rasha’s Tomb just high enough to drop (item)level 20 items. 
The required level to equip gear has nothing to do with it’s “ilvl” (item level). ilvl is a hidden number that you cannot see in the game.