Personally I wouldn't worry?
My old G40 never used to get to temp! It various coolers on it tho and only really got hot when I drove it hard
It will take longer to get in these months due to cold air etc
Intercooler will be cold as its been sat
Air going in will be cold
Block will be cold as its been sat....my point being that big chunks of cold metal will take time to warm up?
If you've got a up rated IC too then obviously it will take its time
You know when a thermostat will stick when you start getting problems with coolant lights, I personally wouldn't worry and shows you that all your potential cooling agents are working
But at the same time what's a thermostat cost? About £15?? May be worth it for your peice of mind tho
Hope that helps
Jack