In reply to Postmanpat:
http://www.nhs.uk/Conditions/Frostbite/Pages/Introduction.aspx
A chilblain? Though they tend to be red, shiny and rather itchy, and not filled with fluid...
If it's actually a blister (i.e. a fluid-filled sac of skin), then it may simply be a normal friction blister; with cold toes, you may not have noticed the rubbing causing the blister*.
I've never seen a frostnip or frostbite blister other than in photos, but all the pictures I can recall have been black, admittedly, usually some time after the freezing has occurred, and the skin has died. NHS link above suggests superficial frostbite might give a red, itchy blister (in contrast to a friction blister which isn't generally itchy or red (except around the margins), IME).
I think I'd treat it like any other normal blister. If it doesn't start to subside normally in a day or two, or starts to go black, or become infected (hot and red), go and get it seen to...
* I have Raynaud's, so my feet regularly get very cold when skiing (white, waxy and cold; I tested them with a pulse oximeter once: no pulse, 0% blood O2 saturation...). Chilblains are rather common, but, so far, I've had nothing worse than that. I have had black toenails from the toes hitting the ends of my boots...
Hot aches for me are associated with being cold, and warming up quickly, causing cold digits to warm very quickly. If I warm up gradually, I don't get hot aches. But that could be due to the Raynaud's... So your lack of hot aches may not rule out your toe having been very cold.
IANAM...