I've lived where I have for the past 2 years and recently a guy has moved into a flat underneath me.He seems single and the other day,passed me his phone number in the hallway.At first,I was a bit shocked and didn't think to do anything,however,we both appear single,why do I feel like this is a mistake ready to happen? He seems lovely,is fit and very polite,is it just too close for comfort if things go wrong?