No it is very intriguing to see how they are doing and curiosity is not necessarily a bad thing. Especially if you still care about them in at least a friendly manner then it isn't wrong
Do you think it is wrong to want to see your teenage love again?
It depends though, have you moved on and settled down with someone else?
Then seeing your old flame might through a spanner in the works and ruin what you have going for you.
Love is a mysterious thing, and we never forget our first romances - so what you are feeling is normal. But acting on those impulses might not be wise, depending on the circumstances.