I grouted my new ceramic tile floor on Friday. I mixed the grout according to instructions (Hydroment), including waiting 15 minutes after mixing and mixing again to insure good color mixing. I applied the grout properly and it looked very good as it was drying. Saturday I was wiping the excess grout off the face of the tile and noticed the grout lines had white streaks in the very light beige grout. What did I do wrong? How can I fix it without digging out the grout?