Chloe's been exactly the same, she started brilliantly, had about two weeks where she did great, then went back to wetting herself all the time, so we stopped, left it for a month or so, then tried again, the second time was much easier, and we had a month with no accidents, even being able to go out all day and her use the toilets and no accidents, then since last Saturday she's been having accidents every day, she had 3 yesterday, I'm not going to stop this time though, I've explained to her today that I want her to use the toilet/potty and have made a big fuss everytime she's been as we'd kind of stopped doing that as she was doing so well.
Anyway, kind of went of on my own ramble there, but in answer to your question, yes I think it is normal, some children get there straight away, other's take a bit longer, she'll get there in the end x