Yet another superficial clot; could it have been caused by the cold?

So, yeah, as the title suggests I developed my third superficial clot this last weekend (which may or may not have become a DVT; I'll find out today. Whee!), this time in my right ankle. No injury there that I am aware of. However, I live in the midwest where we've been dealing with bitter cold and snow. Both last Friday and Saturday I was out shoveling snow off my drive and porches, and I will admit that I wasn't wearing the best footwear for it - I have some heavy duty boots, but I was lazy and put on some low cut shoes (and, once, crocs), and quite a few times my feet were pretty deep in the drifts. I know that cold causes veins to constrict, and given that my ankles were right there, practically in the thick of it, is it possible that my being out there could have caused this most recent clot? I've asked my doctor but didn't but never got a reply back about it.