i got a teeth whitening kit called Day White and it came with 3 syringes of bleaching gel. i'm supposed to use it in my retainer for 30 minutes at a time for about 3 days.

today was the first day and i did what it said to do. after the whitening was done and i brushed my teeth, my teeth appeared spotted and white in certain areas. is this normal for the first day? please i want to know if this is normal and will go away in a day or so. please answer!, thanks.