Playing Vinyl in a Cold Room

No mc I doubt it. The mass of the elastomer is very low. It will revert to room temp very quickly. Alex just put ear muffs on it:) 
You need to put a radiant heater in the basement or move the system. I keep our house pretty cold in the Winter. No higher than 66 degrees. I have never noticed a problem with any of my cartridges. So, you might also consider getting another cartridge saving the EMT for warm Summer days. 
With a heater near the turntable you risk forming a temperature gradient across the record. This is how warps are made. 

@millercarbon wrote 

If you're going that way: below. Heat rises

The plinth would act as an insulator, therefore, you are better off having the light bulb above the table so that the electromagnetic radiation has a direct line to cartridge.  

Alex
It sounds like the suspension has hardened somewhat and the slightly cooler temps are highlighting this.
I do not consider 65 to be cold at all and I regularly play records when the temp is a fair bit lower in my room, say high 50,s.
I do let the system warm up for an hour and have a heater.... Pointed at me..lol.

A small electric heater. Don't make more of it than necessary. From an old old old listener. In two weeks it won't matter. Something else will. Don't stress.

The mass of the elastomer is very low. It will revert to room temp very quickly. Alex just put ear muffs on it:)

Made me go and check. OP bought a nude. How inconsiderate. Oh well, it'll warm up all the faster.

My Koetsu has a nice big brick of a body around it. Think I'll give it a minute or so to get nice and warm. Then another few minutes for the heat to sink in through all that quality Japanese aluminum and whatnot. Then have a listen. So in other words same warmup as usual for everything else, only tonight for the first time physically heating the cartridge up. Gosh for the first time kinda wishing I had one of those trick temp readers. Oh well. New trademark: Go and touch. You will feel.