We have started using Agile/Scrum in a team of 4 developers. We did our story estimations and ordered the stories Primed stories in the product backlog. We started with the point based estimation on the complexity from 1 to 5, instead of usual 1,2,3,5,8,13.... and so onAfter working on a couple of the stories we felt that some of the stories that was estimated at 4 point should only be 2 while the other which were estimated at 2 are a lot more complex and should have been estimated as 5. I would like to know:Is it Ok to change our story estimates in the middle of the iteration? Is it Ok to use the current estimation points from 1 to 5, instead of usual 1,2,3,5,8,13.... and so onAlthough I personally feel that it should be no for both the cases but I need to back myself up as my own understanding is not very clear.(Any good ref material would be good though!) 
Is it Ok to change estimates in the middle of an iteration?
project management;agile;estimation