Those are probable railed, but it could also be that just the center of the base is worn down. Someone PM'd me about racing skis supposedly being railed intentionally. I asked some shop guys that I knew and they thought that it might be this type of tune:
This is different than a truly railed ski. On a true railed ski, the concave would extend all the way out to the edge. Charlie's pic doesn't have light bleeding through all the way to the edge so it may not be truly railed. Ptex is softer than metal so this will naturally happen to skis over time. If you throw a true bar on your ski and it looks like the picture that Charlie posted, I would say that it is worth the time to get them tuned. Again, find a shop with a precision stone grinder and guys who know how to use it without doing irreparable damage to skis. Ask them to put a 1 and 1 on your skis and ask them to detune a little and wax them. If they look at you like you are speaking a foreign language; take your skis somewhere else.