It was quite a cold night (it did not stop me wearing my flip flops though!) and the pastor said:
"If anybody has cold feet, you can put your shoes on. You don't have to take your shoes off tonight."
A polite gesture. Personally, I would assume that if people know they need to take their shoes off, they will bring slippers if they are worried about getting their feet cold. However, if somebody in socks asked to put their shoes back on when it was cold, I would not make a fuss. If they were not wearing socks, I would offer to lend them some first though.