OK, the guy was probably just making conversation but what he said initially came across as a really cheesy pick-up line. It makes a good story at least. Here's what happened...

I was on a group ride this evening. I passed a couple of guys on a climb and just after that ended up stopping at a light. One of the guys that I had passed came up next to me and started chatting.

Him: so when did you have the operation?
Me: operation?!?
Him: you know, to have that baseball implanted into your calf
Me: oh, that (I have some pretty big calf muscles)
Him: what are you, one of those iron, um, people or something?
Me: me an ironman? uh, no
Him: so how'd you get those calf muscles?
Me: I run too and I'm a toe-runner. Not the best running form but it really builds up your calves.
Him: oh

Light changes and we ride on. No more conversation other than a few comments about the ride, the heat, etc. Which is why I decided he wasn't trying to hit on me, just complimenting me in an odd kind of way.