I was in a similar situation to this when I first started sixth form, instead of going to the same secondary school as the rest of my primary school I went to the one in the next town (because it was known for having much better results etc.) I didn't see anyone from my Primary School for 5 years but getting back in touch was fantastic, we all found out that we had way more in common than we did before and so many more of them seem to like me now...
I would say, go for it, speak to them. You will not regret it.