One years old teeth!

Hello girls! For bedtime I did the regular routine, and as I was brushing my daughters teeth I always check them because I’m so scared of anything happening lol so I checked and on one of her front tooth it LOOKED like two white spots VERRRY light but I saw something! I than tried brushing it there in that specific area again and my daughter started crying because her toothbrush is a little rough and I was being a little on the not soft brushing side. (Going to buy her a softer brush) THEN I tried with my finger and when I checked again it looked gone! So what could that have been?? I do brush my daughters teeth twice a day and if she has anything sweet during the day I brush them after that! I highly doubt it was a sign of a cavity but just wondering what that could have been. Didn’t look like any type of food neither. She did drink milk before but I’m not sure if milk can get “stuck” on your tooth like that?