Subfloor for under tile

We had water damage during our house being a rental (manager didn't tell us) so we had to rip out bathroom apart and redo it. We had a contractor come in and fix the joist issues (one was rotted, another was half missing from the original construction) and he replaced the subfloor that needed cutting out with two pieces. One matches exactly to the height of the rest of the subfloor. The other, larger piece is slightly off. I can feel the height difference. Maybe 1/16". My question is, since I'm going to put backer board on the floor and then tile, does this matter? The last thing I want is to have tiles cracking because my subfloor isn't perfectly level. Equally, I don't want to mess with it if it's not an issue.