4weeks pp

Went to my postpartum appointment a week ago ,got checked by a student while midwife next to him she said i was healed and she seen no stitches , she put in my nexplanon and said wait a week and i can have intercourse  with condom that it was fine, had intercourse today and i bled.. Husband said he seen a stitch .. Is it possible she didnt see the stitches if they were still there ?? Could i have reopened?..