Cheating?

The other day I got into my boyfriend's car and it smelled very strongly of perfume. I jokingly said that it smelled like cheap perfume in his car and asked whose been in there. He said that he couldn't smell anything and said that the only people who have been in the car have been his 2 guy friends. He said that it may have one of his guy friends that left the perfume smell in the car because his girlfriend wears a lot of perfume, but the smell was so strong. I'm just a little worried because we live long distance. I've never really had any doubts about him before, but it doesn't make sense that the passenger side of his car smells like woman.