This is reasonably common and not a problem. You are probably not helping by squeezing your nipples - that is stimulating them and will slow down the process of the milk stopping altogether. I would suggest that you stop squeezing them.
I wouldn't squeeze mine often at all. Every now and again I would wonder if I still had any milk so would give them a squeeze, but it may have been 6-12 months since I had last done it. I have no idea why mine never dried up completely!