I think it's completely normal.
There are things that remind me of different exs that relate to when I was with them, songs, places etc.
Every relationship is different. You won't be exactly the same going into the next so you will come across in a different way - it's just how we develop as a person.
Don't be afraid of entering relationships for the fear that they may end, as from the start you'll be picking at things that really aren't a big deal, basically thinking it will before it's even started.
Just relax, life is one big game and there's absolutely no reason to be annoyed at small things. Take things, like this, as they come.