Is it normal for water to pool up in small pockets of your shower floor and take 10-20 min to drain?

Sort of a follow up to a question I posted yesterday... Water is pooling up in our brand new shower floor. Have been going back and forth with my contractor on this and he's willing to fix it, but he claims this is the first time in 20 years he's had to return to a job to fix a shower floor and that some water pooling is normal. Seems like it wasn't done right if there are large pools of water scattered around the floor after a shower.