The only reason that boys like blue and girls like pink, and boys like trucks and girls like dolls, is because it's so violently and viciously shoved down their throats at an early age that they conform to it without realizing it. How many people do you know will paint their babies room pink if they know they're having a boy? Exactly.
Children attach to items at this age out of comfort, not out of anything else. Your son chose a doll, others choose blankets, teddy bears, etc. So I guess the question is, are you going to allow the people you surround yourself with to judge your son, or make him feel like he's less of a "man" (even though he's obviously a child and has no knowledge at all between male, female, or gender identity) because he likes dolls? If not, then by all means, let him rock a doll. If you think the people around you are going to think less of you because you allow your child comfort, you can choose to take the doll away, or re-evaluate who you surround yourself with.
(By the way, gender identity isn't established until well past 32+ months)