Dreams involving old classmates can often reflect our feelings about past relationships, nostalgia, or unresolved issues. Seeing your old classmate, especially someone you are worried about, might indicate that you are processing your concerns about them and perhaps wishing to reconnect or check in on them.

The setting of the dream, being at school, suggests themes of learning, growth, or revisiting your past. This could symbolize a desire to reflect on your own life experiences or the lessons you've learned since your school days.

The fact that your classmate appeared taller could symbolize growth or changes that have occurred in their life, or it may represent your own feelings of growth and maturity since you last saw them.

Overall, this dream might be prompting you to reach out to your old classmate if you feel comfortable doing so. It could also be a reminder to reflect on your current friendships and how they compare to the past. Consider what emotions this dream stirred up for you and how they might relate to your waking life.